Single-dose BNT162b2 mRNA COVID-19 vaccine significantly boosts neutralizing antibody response in health care workers recovering from asymptomatic or mild natural SARS-CoV-2 infection. (July 2021)

• Record Type: Journal Article
• Authors: Vicenti, Ilaria; Gatti, Francesca; Scaggiante, Renzo; Boccuto, Adele; Zago, Daniela; Basso, Monica; Dragoni, Filippo; Zazzi, Maurizio; Parisi, Saverio Giuseppe
• Is Part Of: International journal of infectious diseases. Volume 108(2021)
• Page Start: 176
• Page End: 178
• Publication Date: 2021-07
• Subjects: Health care workers -- BNT162b2 mRNA COVID-19 vaccine -- Neutralizing antibody response; Communicable diseases -- Periodicals; Communicable Diseases -- Periodicals; Communicable diseases; Periodicals; Electronic journals; 616.9
• DOI: 10.1016/j.ijid.2021.05.033
• Languages: English
• ISSNs: 1201-9712

Abstract

Highlights: SARS-CoV-2 neutralizing antibody (NtAb) titres in health care workers (HCWs). After 313 days from a mild, asymptomatic infection NtAbs are often still detectable. One vaccination dose strongly boosts NtAb titers in previously infected HCWs. One dose boosts NtAbs in previously infected more than two doses in uninfected HCWs. Second dose significantly boosts NtAbs elicited by first dose in uninfected HCWs. Abstract: Objectives: To measure SARS-CoV-2 neutralizing antibody (NtAb) titres in previously infected or uninfected health care workers who received one or two doses of BNT162b2 mRNA COVID-19 vaccine. Methods: NtAbs were titrated as dose-inhibiting 50% virus replication (ID50 ) by live virus microneutralization. We evaluated 41 health care workers recovering from mild or asymptomatic infection at first vaccination dose (T1_inf) and 21 days later (T2_inf). Sixteen uninfected health care workers were evaluated 20 days after first dose (T2_uninf) and 20 days after second vaccine dose (T3_uninf). Results: At T2_inf, but not at T1_inf, there was a significant correlation between days from diagnosis (median 313, interquartile range 285–322) and NtAb levels ( P = 0.011). NtAb titres increased at T2_inf with respect to T1_inf (1544 (732–2232) vs 26 (10–88), P < 0.001). Similarly, there was a significant increase in NtAb titres at T3_uninf compared with T2_uninf (183 (111–301) vs 5 (5–15), P < 0001). However, NtAb levels at T2_inf were significantly higher than those at T2_uninf and T3_uninf ( P < 0.0001 for both analyses). Conclusions: A single vaccination in people with mild or asymptomatic previous infection further boosts SARS-CoV-2 humoral immunity to levels higher than those obtained by complete two-vaccination in uninfected subjects.