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Journal of Infection
Pre-proof, accepted manuscript
Main points
Whether SARS-CoV-2 infection confers immunity to reinfection is uncertain
The ‘second wave’ of transmission offered an opportunity to examine this
We observed no symptomatic reinfections in a cohort of healthcare workers
This apparent immunity to re-infection was maintained for at least 6 months
Further studies are required to define immunological mechanism(s) and durability
Also
Immunity to seasonal coronaviruses is (probably) maintained for up to 12 months
The study
N = 11,103 healthcare workers, documented evidence of previous infection status
First wave
March to April 2020
Second wave
October to November 2020
Newcastle and North Tyne
RT-PCR testing, all HCWs with symptoms, since early March 2020
Extensive IgG antibody testing, 937 / 11,103
Infected group
N = 1,038, with evidence of previous infection (positive PCR and/or Ab)
Non infected group
N = 10,137 without (negative Ab, without positive PCR)
Endpoint analysis, symptomatic SARS-CoV-2 infection
Up to 20th Nov 2020
2,243 HCWs underwent PCR testing for symptoms
128 had previous confirmed SARS-CoV-2 infection
2,115 had not had previous infection
In those previously infected, median of 173 (IQR: 162-229) days from first positive PCR/antibody result
Previous infection group
Test positivity rates, 0% (0 out of 128)
No previous infection group
Test positivity rates, 13.7% (290 out of 2,115)
(less than 0.0001 2 test)
One in 10,000
Asymptomatic PCR screening
N = 481 HCWs
With past infection
N = 106
Positivity rate = 0% (0 out of 106)
Without past infection
N = 375
Positivity rate = 5.9% (22 out of 375)
Conclusion
Immunity is maintained for at least 6 months
Infection appears to result in protection against symptomatic infection in working age adults, at least in the short term.
This is consistent with
The low rates of reinfection reported in the literature
The reported ability of vaccines to protect with high efficacy against symptomatic SARS-CoV-2
