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COVID-19 outbreak in a vaccinated deployed military population
  1. Richard James Stuart Elston1,2,
  2. C Pennyfather1 and
  3. S Peppin1
  1. 1 RAMC, British Army, London, UK
  2. 2 4 Squadron, 4 Armoured Medical Regiment, Salisbury, UK
  1. Correspondence to Capt Richard James Stuart Elston, British Army, London SW1A 2HB, UK; re1105{at}

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COVID-19 continues to threaten deployed forces, through both the physical illness and consequent isolation.1–3 It may have been hoped vaccination would reduce the impact of COVID-19 on deployed forces.4 However, this may not be the case. This report describes an outbreak among a vaccinated population. The outbreak is of further interest as few of the patients experienced the big three COVID-19 symptoms.

Twenty-six UK service personnel (SP) deployed to a remote location in West Africa in July 2021. Upon arrival in the country, all SP were isolated in households of six to seven; to leave isolation, SP had to perform a negative PCR COVID-19 test after 7 days in isolation.

Once in the location, the 26 SP were accommodated in 10 rooms spread across three buildings. There was one communal dining room where everyone ate together. During the day, the teams worked outdoors teaching a partner force across two sites.

One month after arrival in the location, a COVID-19 outbreak occurred. Fifteen of 26 SP contracted COVID-19. Thirteen cases were confirmed by PCR. Two SP tested negative on PCR but were classed as cases as they had very similar symptoms to all PCR-confirmed cases. It is unclear exactly where the outbreak came from, the first case was in a member of the sustainment team who interacted with contractors and occasionally visited the market to buy food. It is very unlikely that it had come from the UK as there was no contact with anyone from the UK in the preceding month. It is also unlikely that it had come from the training audience as they all tested negative on lateral flow test 2 days after the outbreak started.

Of the 15 cases, 11 were double vaccinated, (14 with AstraZeneca and 1 with Pfizer), the remaining 4 had had at least one dose of vaccine. All double-vaccinated SP only had 4 or 5 weeks between their vaccinations. All SP received their last vaccine at least 5 weeks before infection. The two PCR-negative cases had received their last vaccination over 20 weeks ago. Table 1 shows vaccination status and symptoms.

Table 1

Vaccination status and symptoms of all UK SP

These results confirm double-vaccinated SP can have a symptomatic COVID-19 infection and infect others. Although no individual was severely unwell, activity had to be suspended during isolation. Periods of isolation can have a significant negative effect on Short Term Training Teams who typically deploy for 6 weeks. Commanders and medical officers should take this into account when planning.

While vaccination showed no effect at decreasing the likelihood of infection, no SP who had had previous PCR-confirmed COVID-19 was a case. Of the 11 individuals who were not cases, 5 had previously had a positive PCR test.

Only four patients experienced any of the big three COVID-19 symptoms (high temperature, cough or loss of taste/smell) (see Table 2). When these symptoms did occur, it was at least 48 hours after the first symptom. All 15 patients felt generally unwell, 13 had runny noses and 7 sore throats. This is consistent with result from the ZOE Study which found these symptoms to be more common in patients who were double vaccinated or infected with the delta variant.5

Table 2

Frequency of symptoms experienced by UK SP

This shows clinicians can no longer rely on the big three symptoms as a tool for ruling out COVID-19 which must be considered in anyone presenting with minor symptoms. This poses a challenge to clinicians as COVID-19 cases must be isolated early to halt an outbreak. However, over-reacting and isolating all patients who might possibly have COVID-19 and their contacts can also be harmful to operational effectiveness. Prompt testing is invaluable.

This outbreak shows the challenges of COVID-19 are as present now as ever in the deployed Role 1 setting. The vaccination does not prevent SP from contracting or passing on the virus and the varied symptoms make diagnosis harder than ever. The chain of command and clinicians should bear this in mind when setting Force Health Protection measures and seeing patients.

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  • Contributors CP and SP collected the patients' symptoms and vaccination dates. RJSE conceived and wrote the article.

  • Funding The authors have not declared a specific grant for this research from any funding agency in the public, commercial or not-for-profit sectors.

  • Competing interests None declared.

  • Provenance and peer review Not commissioned; internally peer reviewed.