Cases of COVID-19 reported including deaths in care home residents after full-course vaccination

Simon Collins, HIV i-Base

Several recent studies have reported cases of COVID-19 in residential care homes despite full-course mRNA vaccination, including the B.1.351 variant. [1, 2]

Other studies have also reported significantly lower humoral responses to COVID-19 vaccines in some people with reduced immune function, including those older than 80 years. [3]

A paper published in CID reported an outbreak of the 501.v2 (B.1.351; South African) variant in an elderly nursing home in France. All non-vaccinated residents (5/5) became infected compared to half (13/26) who had been fully vaccinated (two doses) with the Pfizer mRNA vaccine (BNT162b2). COVID-19 was serious in 4/5 and 2/13 of these two groups respectively. [1]

This study included 31 residents and 59 staff. The first case was in a 92 year-old resident, with 17 residents testing positive over the next three weeks. Vaccinated residents had received their second vaccine dose from 4 to 26 February,

Only 19/59 staff were fully vaccinated. with 1/19 becoming infected vs 10/40 unvaccinated staff. No staff developed serious COVID-19 symptoms but the outcomes for residents who had received two vaccine doses was more serious.

Although 2/13 cases were asymptomatic, 9/13 developed mild to moderate symptoms and 2/13 2 (15.4%) progressed to severe disease and died, secondary to acute respiratory distress syndrome (ARDS).

A second more optimistic but still cautious study included a retrospective review from 280 care homes in the US reported in a letter to the NEJM. This included more than 18,000 vaccinated (13,000 of which had received both doses) and approximately 4,000 unvaccinated residents. [2]

The incidence of infections declined significantly over time in all groups. Vaccination were mRNA: 80% Pfizer, 20% Moderna.

In those receiving one dose there were 822 incident cases (4.5%) within 0 to 14 days and 250 cases (1.4%) at 15 to 28 days. In those who received both doses there were 130 incident cases (1.0%) within 0 to 14 days and 38 cases (0.3%) after 14 days. Cases also decreased in unvaccinated residents from 173 cases (4.3%) within 0 to 14 days after the first vaccination clinic to 12 cases (0.3%) at more than 42 days after the clinic.

While showing levels of community protection in those who were unvaccinated, the paper showed infections after receiving both doses.

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References

1. Bailly B et al, BNT162b2 mRNA vaccination did not prevent an outbreak of SARS COV-2 variant 501Y.V2 in an elderly nursing home but reduced transmission and disease severity. Clinical Infectious Diseases, ciab446. DOI: 10.1093/cid/ciab446. (16 May 2021).
   https://academic.oup.com/cid/advance-article/doi/10.1093/cid/ciab446/6276392
2. White EM et al. Incident SARS-CoV-2 Infection among mRNA-Vaccinated and Unvaccinated Nursing Home Residents. NEJM. DOI: 10.1056/NEJMc2104849. (19 May 2021).
   https://www.nejm.org/doi/full/10.1056/NEJMc2104849
3. Collins S. Low responses to mRNA COVID-19 vaccines in those older than 80 vs <60 years and in recipients of solid organ transplants. HTB (3 May 2021).
   https://i-base.info/htb/40502