Antibody response to 1 dose of SARS-CoV-2 mRNA vaccine in previously infected HCWs

According to a research letter published on JAMA Network, antibody titer responses to a single dose of mRNA vaccine were higher in health care workers (HCWs) with previous SARS-CoV-2 infections than in those without. Given the global vaccine shortage, investigators believe this finding could affect single-dose vaccine strategies for previously infected people or help lower their place on the priority list.

A total of 3816 HCWs were included in a Serosurvey study conducted in August 2020. Of these, 151 HCWs were contacted randomly and 59 volunteers were enrolled. In the volunteer group, 17 were previously identified as SARS-CoV-2 IgG antibody negative (Ab negative), 16 IgG positive with asymptomatic COVID-19 (asymptomatic) and 26 IgG positive with symptomatic COVID-19 (symptomatic) . . Participants were vaccinated with either the Pfizer BioNTech or Moderna vaccine and their blood was drawn at 0, 7 and 14 days.

On each sampling day, the median reciprocal half-maximal binding titers in the asymptomatic (208, 29,364 and 34,033) and symptomatic (302, 32,301 and 35,460) groups were higher than in the Ab-negative group (<50, <50, and 924) (P < 0.001 for each). The median reciprocal ID99 virus neutralization titers on days 0 and 14 were 80 and 40,960 for the asymptomatic group and 320 and 40,960 for the symptomatic group, which in turn were both higher than those of the Ab negative group (<20 and 80) (P <. 001 for everyone).

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The study was limited by a small sample size and potential biases as the sample may not be representative of the original population. In addition, the data on the effectiveness of the vaccine were insufficient.

Investigators concluded that HCWs with prior COVID-19 (as diagnosed by laboratory-confirmed serological tests) had higher antibody titer responses, which could inform vaccine prioritization and a potential single-dose vaccination strategy.

reference

Saadat S, Tehrani ZR, Logue J, et al. Binding and neutralization antibody titers after a single vaccination dose in health workers previously infected with SARS-CoV-2 JAMA. Published online March 1, 2021. doi: 10.1001 / jama.2021.334