The COVID-19 pandemic arising in 2020 changed the world as we know it. The way we think about and execute overseas expeditions has and needs to take account of this. With the advent of vaccines, the world is slowly opening up again. However, with global inequity of vaccinations and rapidly appearing new variants of COVID-19, the purpose, justification and accomplishment of any expedition require careful consideration.
Endorsed by the Royal Geographical Society, this guide is for teams looking to go on expedition during the COVID-19 pandemic. Considerations for each step of the expedition are discussed with possible suggestions and protocols on how to pragmatically factor these into the expedition plans.
- Should this expedition take place?
- COVID-19 risk assessing
- Minimising the risk of contracting COVID-19 pre-expedition
- Expedition Amendments
- Roles and Responsibilities
- Agreeing to go on expedition
- Minimising transmission risk on expedition
- Policy for COVID-19 symptoms on expedition
- Expedition closure
- Useful sources of information
- Example protocols
- Suggested COVID-19 medical questionnaire
- About the author
- The urgency of the expedition – why does it need to be done now?
- The overall COVID situation in the host country
- The health and risk to each member of your team
- The health and risk to the in-country team and local communities you are visiting or passing through
- The extent that COVID restrictions will limit what can and cannot be done on expedition
- The additional financial cost of going during a pandemic
- The mental health/anxiety impact on team members and in-country teams
- The duration of the expedition and time needed for potential quarantining
- Availability of vaccines for expedition members and in-country teams
The expedition stakeholders need to question: should this expedition be taking place and is now the right time? This will depend on many factors, not least the overall aims of the expedition itself.
Morals and ethics
When deciding whether to proceed with your expedition, you must weigh up the benefits of going on expedition now versus the health risks to the expedition members and the host community. This is covered further in the COVID-19 risk assessment.
COVID-19 will likely impact upon the parameters of your expedition. If the expedition plan was for your team to integrate with local communities or travel across borders you may find you are unable to do so during a pandemic. Depending upon the situation in the host country, it may be sensible for your team to significantly limit the amount of contact they have with locals to minimise risk. Are any of the restrictions COVID-19 puts on your expedition going to impact your ability to complete the expedition’s aims?
The timeframe of the expedition may be impacted by COVID-19. For example, if someone on your expedition develops symptoms of COVID-19 they will have to self-isolate and if they test positive this will be for a minimum of 10 days. Similarly, if the host country becomes red-listed by the UK government and you need to quarantine on returning to the UK, or the host country’s government changes its travel policies, this will lengthen your expedition.
The cost of an expedition during a pandemic may well be higher than it would be if it were postponed. Additional costs may include COVID-19 testing, travel insurance, PPE, additional medical equipment and potential quarantine on both entering the country and if expedition members develop symptoms and need to self-isolate (if not covered by insurance).
Expedition member considerations:
- Each team member’s medical and drug history including age, fitness level and other medical conditions.1,2,3,4
- Have they previously tested positive for COVID-19?
- Do they suspect they have previously had COVID-19?
- Have they had a COVID-19 vaccine? How many? Which vaccine? How effective is this vaccine?
- Are they at high risk from COVID-19?1,2
- Who is in their household? Are they at high risk/shielding?
- Their occupation and who they work with.
A COVID-19 risk assessment should be conducted for each individual on expedition, this is especially important if the expedition is going to areas with high levels of COVID-19. It should include each member’s risk of developing symptoms, becoming more seriously ill and developing complications.1,2,3,4 A suggested COVID-19 medical questionnaire can be found below.
All expedition members should be informed of the COVID-19 rates in the host country/area and at which points during the expedition the risks of infection are highest. Expedition members should be informed of COVID-19 risks and worse case scenarios – for example, becoming seriously unwell with COVID-19 whilst in a remote environment with no access to a hospital. They should each understand and acknowledge the risk before deciding whether to be part of the expedition.
You may want to consider making it a prerequisite that all expedition members must have had a full course of COVID-19 vaccinations before the expedition’s start date or they will not be allowed on expedition.
Local community considerations:
- Is the local population a particularly vulnerable community?1,2,3,4
- What is the distance to the nearest hospital with definitive care for COVID-19 patients?
- Is there equitable health provision for UK and in-country teams including insurance/finance for treatment/travel and loss of work?
- Are individuals from the community likely to seek medical help if they become unwell with COVID-19? This is a complex question, with many cultural nuances, but does need consideration by the expedition stakeholders.
- Is the community currently free of COVID-19 with your expedition risking being a new source of infection?
- If so, are all isolation and testing measures in place and agreed to be of gold standard?
- If known, what is the natural immunity to COVID-19 in this population, and does this change any of the expedition planning?
- Are the local community social distancing and if so, is this practical on expedition?
- Is PPE available and is it practical to use this on expedition?
- What percentage of the local population is vaccinated and has this been shown to be effective?
- Are there cultural barriers to vaccination and COVID-19 information?
- To what extent will your expedition integrate itself with this community?
- How likely is your expedition to bring new cases of COVID-19 to this community – are you travelling to high-risk areas before going here?
Information such as this may be difficult to find or not available. However, it is important to take each of these points into account when assessing the risk to the host community. You might want to seek out information on whether the community has a large population of individuals with risk factors for severe COVID-19 such as: high age, cardiovascular disease, diabetes, respiratory disease (including severe asthma), obesity, a history of haematological malignancy or recent other cancer, kidney, liver and neurological diseases, and autoimmune conditions.1
Low-income or middle-income countries (LMIC) considerations:5
- The distance to the nearest hospital/medical centre
- The capacity of the nearest hospital/medical centre
- How easily available is transport to the hospital/medical centre
- The financial implications of treatment and travel
In LMICs professional medical care can be days away. Depending on your destination, transport to medical centres may be difficult. There may be little access to private vehicles and minimal/unreliable public transportation or ambulance services.5,6,7 You may wish to carefully plan your mode and location of evacuation in the event an expedition member becomes unwell.
What are the living conditions of the local team and host community like? Are they well ventilated/shared tents/densely populated?
Ideally, a separate risk assessment should be performed for each different community you may encounter. If after completing each risk assessment you deem that the risk of your expedition introducing a new (and perhaps different) strain of COVID-19 is high, you may wish to rethink this section of your expedition.
If you’re only passing through a (high-risk) community is there a different less risky route you could take? Or if you must come into contact with a (high-risk) community, what can you do to negate the risks you pose? Can you quarantine for several days before travelling to this community? Can you ensure you keep your distance from them? Can you realistically wear PPE for long periods in this environment?
- Expedition members self-isolating in the days prior to the expedition to reduce risk
- Expedition members having appropriate/country-specific COVID-19 tests prior to the expedition (also consider the timing of the tests – will you need documented proof of a negative result?)
- Has an expedition member been in close contact with an individual who has since tested positive for COVID-19?
- How are expedition members getting to the departure venue?
- Changes or additions to the medical kit
Having all members of the expedition (and their household) self-isolate in the run-up to the expedition is an effective way to negate the risk of an expedition member catching COVID-19 before the start date. You should check how high your local infection rate is to aid this decision. In reality, the rates may be very low, and it may be impractical to self-isolate for several days prior to the expedition. Use your sensible judgement – being more conscious about social distancing and minimising close contacts prior to the expedition may be all that is necessary.
If you do decide that expedition members should self-isolate prior to the expedition, check the current guidance on how many days this should be for. You may wish to consider having all team members isolating together before the expedition – this could be good for team building and may reduce the likelihood of an expedition member becoming apprehensive about the expedition and deciding not to go at the last minute. On the other hand, if any individual brings COVID-19 to the group this may quickly spread and mean the entire expedition must be cancelled.
Expedition members should take COVID-19 tests before they leave the UK. Testing before international travel may be needed by law before being allowed entry to that country. This sort of COVID-19 testing is not currently available on the NHS and is only available from private providers.10 When booking testing, you should ensure that it is carried out by a laboratory accredited by the United Kingdom Accredited Service (UKAS). To know which type of test to book check the host countries government’s guidelines or the UK governments foreign travel advice.12
Each expedition needs to have a clear policy in case of a positive test result. The expedition member who returned the positive test should follow government advice and remain in isolation for the appropriate time. This may mean that part of your team is unable to go on the expedition. You should be wary of this situation and develop contingency plans. Do other team members possess sufficient skills to fill in for the expedition member who is self-isolating? Alternatively, do you know anyone who could replace this team member and fulfil their role at short notice? It would be wise to have reserves should anyone be unable to travel. Depending on the expedition parameters the individual(s) who tested positive may be able to reconvene with the expedition once they are clear of the virus. This could be factored into the planning but may be too impractical in reality.
How expedition members are getting to the departure venue should be considered. Ideally, they should be driven by car by a member of their household to minimise the risk of contracting the virus. Public transport should be avoided.9 Research has suggested that imported cases of COVID-19 infections from international travel are likely to contribute little to local COVID-19 epidemics. The exceptions are in countries with low COVID-19 rates and large numbers of international travellers, or in countries where epidemics are close to reaching a tipping point, which if reached, would lead to an exponential growth in cases.11 Separate research has stated that the risk of COVID-19 transmissions in flights, especially short and medium-haul flights, is low and can probably be reduced even further by the use of face masks and social distancing onboard.13,14
A final pre-expedition requirement is ensuring the medical kit has sufficient equipment for dealing with a COVID-19 infection.15 This may include: an extra supply of PPE (gloves, mask, apron, eye protection), a pulse oximeter, spare COVID-19 tests, a contactless temperature monitor, hand gel, antimicrobial wipes/cleaning products.
- Does travel to the country/state need to be permitted by local authorities? How far in advance?
- Does permission need to be granted by the country’s authority or the regional one or both?
- Should insurance be in place to cover your expedition’s work (even if it is voluntary)?
- Do expedition members need to be vaccinated before being allowed to enter the country/state?
- What are the travel regulations for the host country?
- What are the travel regulations for returning to the UK?
- Ensure you know the consequences if you are found to be breaching local COVID-19 laws
What are the host country’s regulations when it comes to mandatory self-isolation periods, vaccine passports and COVID-19 testing requirements for individuals arriving from the UK? If you need to quarantine on arrival to the host country how does this work – do you have to organise the place of quarantine and pay for it yourself?12 Again, be aware that these guidelines are constantly changing so keep checking for the most up to date information.
Be wary that countries may be forced to open their borders for financial reasons – to the detriment of health. Consider if this is likely the case in the country you are travelling to – is the host country allowing individuals from countries with high levels of active COVID-19 infections entry? What percentage of the local population is vaccinated? Knowing this will help determine how prepared the country is for an influx of tourists who may bring COVID-19 with them. A country opening its borders for financial reasons will likely lead to COVID-19 rates increasing, and therefore a higher risk of your expedition contracting COVID-19. The knock-on effect of this could see hospitals overrun with less medical provision available should you need it. In this instance, you may wish to consider delaying your expedition.
It is also worth bearing in mind the travel regulations in the UK for when you return. Will travelling to your host country mean you have to self-isolate on returning to the UK? If not, is this situation likely to change?
Lastly, understanding the local laws regarding COVID-19 is essential. Expedition plans may need to be changed or kept flexible and abiding by these laws must be stressed to all team members. Be aware that these laws change frequently so keep checking for the most up to date guidance.
The individual chosen to lead the expedition should be selected as they possess skills (both technical and non-technical), qualities and experiences relevant for the expedition. If appropriate, this too should be the case for the expedition members.16
Responsibilities of the team leader:16
- Supervising and managing individuals and the group
- Making decisions about the best next course of action for the expedition
- Conducting dynamic risk assessments throughout the expedition, including of transport and accommodation
- Managing risk and implementing contingency plans to do so
- Communicating required actions to the expedition team
Competencies required of the team medic/first aid leader should be assessed through a combination of the following:17
- Experience of an expedition of a similar nature
- Activity proficiency
- In-house training and assessment
- A relevant and current national or international qualification or award showing wilderness medicine expertise
- Ability to read and interpret a pulse oximeter
- Have a good overview of respiratory diseases, understand basic treatments and be able to assist in improvising delivery devices; appreciate simple assessments of respiratory rate and shortness of breath and make rational decisions on the need for, and mode of evacuation
- Be able to assess and interpret respiratory symptoms and signs, and differentiate common ailments
- Be able to diagnose a COVID-19 infection, assess the infection’s severity and make decisions regarding the necessity of hospital evacuation
Responsibilities of team members:17
- Taking reasonable care of themselves and others, including actions required of them arising from risk assessment
- Following instructions from the expedition leader
- Bringing concerns about their own safety, health and well-being and those of others to the attention of the leadership team or supervisors
- Complying with the code of conduct of the expedition and that required in the host country.
When buying travel insurance to cover the expedition there are several considerations. At the time of writing this document, the travel insurance situation is still unclear. The following advice is a good basis to start from. It is important you check the travel insurance policy thoroughly before buying in, and ensuring it covers claims related to COVID-19 for:
- Emergency medical costs – it is frequently recommended that you look for medical cover of at least £2m for Europe and £5m for worldwide. You’ll also want to ensure your insurer has a 24hr emergency helpline.
- Repatriation costs
- Disruption and cancellations – including cancellations because you have been told to self-isolate or are diagnosed with COVID-19 just before travelling; at the time of writing few policies include this.18 It is recommended you look for cover of at least £3,000 or the value of your trip. Make sure the cover will reimburse costs caused by delays, missed departures or being forced to remain at your destination for longer than planned (including extra accommodation costs if your trip is extended) – this may come as an add-on to the main policy. Make sure to read the small print as some cancellation policies only cover an incredibly narrow range of circumstances.
- Scheduled airline failure insurance (SAFI) – look for the same level of cover as you would for cancellation. This will cover you if your airline goes bust before you fly. Booking flights over £100 with a credit card also gives you protection under Section 75.
- If the Foreign Commonwealth & Development Office (FCDO’s) advice about travel to the destination changes
Not all policies will cover all of these things, so make sure you know what is covered and what is not. Choose your policy based on the features of COVID-19 cover you think are most vital for your expedition.
If your expedition is travelling to a destination where the FCDO is advising against travel, then it is likely you won’t be covered by insurance.18 The costs will also not be covered if you book a trip while border closures and travel restrictions are in place and these restrictions are not lifted by the time you commence your expedition.
Finally, it is worth bearing in mind ‘excess’ when choosing your cover. ‘Excess’ means if you claim on insurance the excess sum will be subtracted from the amount the insurer pays you. For example, if you had a £3,000 cancellation claim and a £250 excess, you would get paid £2,750 from your insurer. Higher excesses often make the insurance cost for you cheaper but may dissuade you from claiming for smaller amounts.
Due to the changing situation of COVID-19, team members may be constantly questioning whether they actually want to go on the planned expedition and whether it is safe to do so. There comes a point as a group where the decision of whether to go or not is made – this decision is often marked by putting parts of your plan into action, such as buying plane tickets or booking accommodation. We recommend that you and your team set a date in the future on which the group decides together if they want to go ahead on expedition. On this day arrangements such as accommodation and travel can be organised and paid for.
We also recommend that if you decide to go ahead and book your expedition to make a list of criteria, which if met between now and the date the start date of the expedition, would mean you will cancel your trip (such criteria may include infection rates and hospital capacities in the host country).
- Blanket testing all expedition members at predetermined points on expedition
- COVID-conscious transportation protocols11
- COVID-safe protocols are in place for anyone joining the expedition after it has begun
It would be sensible to blanket test expedition members at predetermined points (using the tests packed in the medical kit), such as after leaving a higher risk area, or before entering a new community. If you choose to do this, you need clear protocols about what to do should a positive test be returned (see next section).
COVID-conscious transportation policies could include minimising the use of public transport, reducing vehicle capacities, ensuring the vehicle is well ventilated (windows open).11 Before the expedition you should check whether any transportation policies are already in place in the host country – if they are not you may want to avoid public transport entirely – especially buses or trains where many people may be crowded together in a small indoor space.
Anyone joining the expedition after it has started (such as an individual who is already in the host country) should comply with the policies your expedition has in place to minimise the COVID-19 risk. You should ensure the person joining the expedition has self-isolated for the appropriate time prior to joining your expedition, and they should pass a COVID-19 test before integrating with your group (these are the same policies all expedition members followed).
- A plan for if an expedition member(s) develops minor symptoms of COVID-19
- A plan for if an expedition member(s) becomes more seriously ill with COVID-19
- If a member of the expedition becomes ill and withdraws, will you carry on with the expedition? And does the remainder of the team have sufficient skills to fill in for the absent team member?
If an expedition member develops minor symptoms of COVID-19 they need to inform the expedition leader immediately and be isolated from the rest of the group. All group members should take a COVID-19 test and the team member with symptoms ideally needs a PCR test and a suitable place to isolate until the PCR result comes back. You need to follow the local public health guidance for what to do if someone gets COVID-19 symptoms. If someone falls ill, you should also call your health provider/insurance company to discuss the next course of action.
Remember that COVID-19 symptoms do not necessarily mean you have COVID-19 – there could be other causes; if you are in a malaria-affected area it is important to exclude malaria (with a blood test).22 A team member becoming infected may mean that the expedition member(s) must stay in the country longer than was planned. Once the expedition member has fully recovered, you should check with your health provider that they are fit to travel, before choosing your next steps.
If an expedition member becomes more seriously ill with COVID-19, a medic will need to determine if evacuation to a hospital is necessary. Determining where the nearest hospitals are, their capacity and quality and the local emergency numbers is essential pre-departure.
If an expedition member becomes ill in a remote area, a medic needs to assess whether evacuation is necessary (and by which route: air vs road). Evacuation teams should be alerted that an expedition member has developed COVID-19 symptoms and may potentially need evacuating in the near future. The team member with symptoms should be isolated. In a remote environment, it is unlikely the team will be able to escort the unwell team member back to a safe area where they have easy access to more advanced medical care – especially as it is unknown whether their health will deteriorate. An unwell COVID-19 patient in a remote area will likely need to be evacuated by a specialised team.
It is important to consider the impact an evacuation will have on the remaining expedition team. Will the expedition be able to continue? And indeed, is it safe to do so? Will anybody else be infected as well? You and the team should have discussed whether the expedition would continue if team a member/members are evacuated or withdraw pre-departure. When in the field, factors such as team morale should also be considered. If possible, remaining members should take COVID-19 tests to determine whether they too need evacuating with the symptomatic individual.
In the event a team member falls ill with COVID-19 symptoms and needs care from their team, one individual should be selected as the designated caregiver. They should wear a fitted N95 mask, eyewear, nitrile or latex gloves and a disposable gown/apron when caring for the unwell member.23 If possible (depending on how unwell the infected person is) the infected member should wear a mask or face covering over their mouth and nose when in close contact with the caregiver.
Some patients with COVID-19 are hypoxic yet seem well and lack shortness of breath. These patients are sometimes referred to as ‘happy hypoxics’ or ‘silent hypoxics’. The disconnect between the severity of hypoxaemia and the mild respiratory discomfort a ‘happy hypoxic’ reports is contrary to what a clinician would normally expect in respiratory failure.24,25
‘Happy hypoxics’ may remain clinically well as they continue to compensate for their hypoxia until they reach a point where they can no longer compensate and deteriorate rapidly. Warning signs for impending respiratory failure may include an increased respiratory rate (tachypnoea), signs of hyperventilation and a dropping oxygen saturation.25 Therefore, if a member of your expedition is found to have COVID-19, them reporting that they feel well in themselves and do not feel short of breath is not a reliable measurement of severity. Research suggests paying close attention to respiratory rate and oxygen saturations to establish how severely unwell the expedition member is and how urgently they may need evacuation.25
If your expedition is at high altitude, then oxygen saturations and respiratory rate are likely less reliable indicators of wellbeing.26 Despite some (disputed) evidence suggesting that there is a lower incidence of mortality in patients at high altitude, altitude/hypoxia is likely associated with elevated risks for patients with COVID-19 and therefore descent from altitude is probably advisable.27 Interestingly, some research suggests that COVID-19 transmission is lower at high altitudes, possibly due to the body’s physiological responses to altitude and/or environmental factors – but this too is disputed.28
- After the expedition are team members returning home or remaining in the host country for further travel?
- The current government guidance about re-entering the UK
- Travel insurance
- Follow up
It is common for expedition members to plan further travel post-expedition. Travel insurance to cover this period should also be checked. Re-entry guidelines and protocols should be made clear to expedition members, including whether or not testing or quarantining are required on returning to the UK. Expedition members should have a clear understanding of UK re-entry requirements, and any requirements the host country has on leaving. Expedition members should also be made aware of any special requirements needed if the expedition has travelled through a country on the UK’s banned travel list (‘red list’). They should also be informed of whether the host country is likely or not to become ‘red listed’ by the UK, and if so, how this would change re-entry and indeed whether the host country would allow anyone to leave.
Finally, you should consider following up expedition members 14 days post-expedition to declare if any members of the expedition (UK or host country) develop any COVID-19 symptoms.
European Centre for Disease Prevention and Control (this includes data on hospital admissions and ICUs amongst other things)
The following COVID-19 medical questionnaire should be used IN ADDITION to another medical questionnaire
We recommend cross-referencing expedition member’s medical forms to the known risk factors for severe COVID:
Age, cardiovascular disease, diabetes, respiratory disease (including severe asthma), obesity, a history of haematological malignancy or recent other cancer, kidney, liver and neurological diseases, and autoimmune conditions.1
James Taylor is a final-year medical student at The University of Sheffield. He chose to get involved in the world of expedition medicine during his medical elective. When the pandemic changed his plans he was invited to construct a protocol on how to conduct COVID-safe expeditions by the Royal Geographical Society’s expedition medicine advisory group.
Living on the edge of the Peak District James can often be found climbing, mountaineering and fell-running. He has an interest in Pre-Hospital and Emergency Medicine, and plans to combine his love of the outdoors with medicine by working an expedition medic during his career.
If you have any feedback or comments, feel free to send them to:
c/o Mrs Shane Winser, Royal 1Geographical Society, 1 Kensington Gore, London SW7 2AR; or email: firstname.lastname@example.org
- Williamson EJ, Walker AJ, Bhaskaran K, et al. Factors associated with COVID-19-related death using OpenSAFELY. Nature 2020; 584: 430–436 https://doi.org/10.1038/s41586-020-2521-4
- Hashim MJ, Alsuwaidi AR, Khan G. Population Risk Factors for COVID-19 Mortality in 93 Countries. J Epidemiol Glob Health. 2020;10(3):204-208 https://doi.org/10.2991/jegh.k.200721.001
- Wolff D, Nee S, Hickey NS, et al. Risk factors for Covid-19 severity and fatality: a structured literature review. Infection 2021; 49:15–28 https://doi.org/10.1007/s15010-020-01509-1
- Rashedi J, Mahdavi Poor B, Asgharzadeh V, Pourostadi M, Samadi Kafil H, Vegari A, Tayebi-Khosroshahi H, Asgharzadeh M. Risk Factors for COVID-19. Infez Med 2020; 28(4): 469-474.
- Baart J, Taaka F. Barriers to Healthcare Services for People with Disabilities in Developing Countries: A Literature Review. Disability, CBR & Inclusive Development 2018; 28(4), pp.26–40. http://doi.org/10.5463/dcid.v28i4.656
- Orach CG. Health equity: challenges in low-income countries. Afr Health Sci. 2009;9 Suppl 2 (Suppl 2): S49-S51.
- Peters DH, Garg A, Bloom G, Walker DG, Brieger WR, Rahman MH. Poverty and access to health care in developing countries. Ann N Y Acad Sci. 2008; 1136: 161-71. https://doi.org/10.1196/annals.1425.011
- Lewnard JA, Lo NC. Scientific and ethical basis for social-distancing interventions against COVID-19. Lancet Infect Dis. 2020; 20(6): 631-633. https://doi.org/10.1016/S1473-3099(20)30190-0
- Meara JG, Leather AJM, Hagander L, Alkire BC, Alonso N, Ameh EA, et al. Global surgery 2030: evidence and solutions for achieving health, welfare, and economic development. Lancet 2015; 386 (9993): 569–624. https://doi.org/10.1016/S0140-6736(15)60160-X
- Department for Transport. Coronavirus (COVID-19) testing before you travel to England. [Internet]. 2021 [cited 23/7/21] Available from: www.gov.uk/guidance/coronavirus-covid-19-testing-for-people-travelling-to-england
- Shen J, Duan H, Zhang B, et al. Prevention and control of COVID-19 in public transportation: Experience from China. Environ Pollut 2020; 266 (Pt 2): 115291. https://doi.org/10.1016/j.envpol.2020.115291
- Coronavirus (COVID-19) Guidance and Support. Foreign Travel Advice. [Internet]. 2021 [cited 21/7/21] Available from: www.gov.uk/foreign-travel-advice
- Blomquist, PB, Bolt, H, Packer, S, et al. Risk of symptomatic COVID-19 due to aircraft transmission: a retrospective cohort study of contact-traced flights during England’s containment phase. Influenza Other Respi Viruses 2021; 15: 336– 344. https://doi.org/10.1111/irv.12846
- Freedman DO, Wilder-Smith A. In-flight transmission of SARS-CoV-2: a review of the attack rates and available data on the efficacy of face masks. J Travel Med. 2020;27(8): taaa17 https://doi.org/10.1093/jtm/taaa178
- World Health Organization. Priority Medical Devices List for the COVID-19 Response and Associated Technical Specifications: INTERIM GUIDANCE. World Health Organization, 2020. [Accessed 23 July 2021] Available from: www.jstor.org/stable/resrep27993
- Russell TW, Wu JT, Clifford S, Edmunds WJ, Kucharski AJ, Jit M; et al. Effect of internationally imported cases on internal spread of COVID-19: a mathematical modelling study. Lancet Public Health. 2021;6(1): e12-e20. https://doi.org/10.1016/S2468-2667(20)30263-2
- British Standards Institute, 2007. BS 8848. Specification for the provision of visits, fieldwork, expeditions and adventurous activities, outside the United Kingdom. British Standards Institute, London. 2007.
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- Bulfone TC, Malekinejad M, Rutherford GW, Razani N. Outdoor transmission of SARS-CoV-2 and other respiratory viruses: a systematic review. J Infect Dis 2021; 223: 550-561. https://doi.org/10.1093/infdis/jiaa742
- Leclerc QJ, Fuller NM, Knight LE, Funk S, Knight GM, CMMID COVID-19 Working Group. What settings have been linked to SARS-CoV-2 transmission clusters? Wellcome Open Res 2020; 5:83. https://doi.org/10.12688/wellcomeopenres.15889.2
- Scientific Advisory Group for Emergencies, Public Health England. PHE Transmission Group: Factors contributing to risk of SARS-CoV2 transmission in various settings, 26 November 2020. 18 Dec 2020. www.gov.uk/government/publications/phe-factors-contributing-to-risk-of-sars-cov2-transmission-in-various-settings-26-november-2020
- Chanda-Kapata P, Kapata N, Zumla A. COVID-19 and malaria: A symptom screening challenge for malaria endemic countries. Int J Infect Dis. 2020; 94: 151-153. https://doi.org/10.1016/j.ijid.2020.04.007
- Tian Z, Stedman M, Whyte M, et al. Personal protective equipment (PPE) and infection among healthcare workers – What is the evidence? Int J Clin Pract. 2020; 74: e13617. https://doi.org/10.1111/ijcp.13617
- Wilkerson RG, Adler JD, Shah NG, Brown R. Silent hypoxia: a harbinger of clinical deterioration in patients with COVID-19. Am J Emerg Med. 2020; W.B. Saunders. http://doi.org/10.1016/j.ajem.2020.05.044
- Dhont S, Derom E, Van Braeckel E, et al. The pathophysiology of ‘happy’ hypoxemia in COVID-19. Respir Res 2020; 21: 198. https://doi.org/10.1186/s12931-020-01462-5
- Crocker M, Hossen S, Goodman D, Simkovich SM, Kirby M, Thompson LM. Effects of high altitude on respiratory rate and oxygen saturation reference values in healthy infants and children younger than 2 years in four countries: a cross-sectional study. Lancet Glob Health 2020; 8(3): E362-373. https://doi.org/10.1016/S2214-109X(19)30543-1
- Millet GP, Debevec T, Brocherie F, Burtscher M, Burtscher J. Altitude and COVID-19: Friend or foe? A narrative review. Physiol Rep. 2021; 8(24): e14615. https://doi.org/10.14814/phy2.14615
- Stephens KE, Chernyavskiy P, Bruns DR. Impact of altitude on COVID-19 infection and death in the United States: A modelling and observational study. PLoS One. 2021, 16(1): e0245055. https://doi.org/10.1371/journal.pone.0245055
Featured photograph by Dr Lucy Obolensky, with permission.