Long-lasting neutralizing antibody responses in SARS-CoV-2 seropositive individuals are robustly boosted by immunization with the CoronaVac and BNT162b2 vaccines

Abstract

The durability of circulating neutralizing antibody (nAb) responses to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection and their boosting by vaccination remains to be defined. We show that outpatient and hospitalized SARS-CoV-2 seropositive individuals mount a robust neutralizing antibody (nAb) response that peaks at days 23 and 27 post-symptom onset, respectively. Although nAb titers remained higher in hospitalized patients, both study groups showed long-lasting nAb responses that can persist for up to 12 months after natural infection. These nAb responses in previously seropositive individuals can be significantly boosted through immunization with two doses of the CoronaVac (Sinovac) or one dose of the BNT162b2 (BioNTech/Pfizer) vaccines, suggesting a substantial induction of B cell memory responses. Noteworthy, three obese previously seropositive individuals failed to mount a booster response upon vaccination, warranting further studies in this population. Immunization of naive individuals with two doses of the CoronaVac vaccine or one dose of the BNT162b2 vaccine elicited similar levels of nAbs compared to seropositive individuals 4,2 to 13.3 months post-infection with SARS-CoV-2. Thus, this preliminary evidence suggests that both, seropositive and naive individuals, require two doses of CoronaVac to ensure the induction of robust nAb titers.

Assessment on anti-SARS-CoV-2 receptor-binding domain antibodies among CoronaVac-vaccinated Indonesian adults

“…In addition, our finding was supported by other studies [ 1 4 ], reporting that average levels of neutralizing antibodies in the recovered adults were higher than those in CoronaVac-vaccinated healthy adults. Nonetheless, it is important to mention that the neutralizing antibody responses in previously seropositive individuals could be further boosted by two doses of CoronaVac vaccines [ 4 ], providing a merit of using CoronaVac vaccine to protect against symptomatic COVID-19.…”

“…As prior mentioned, the vaccinated adults in this study were SARS-CoV-2 naïve subjects, hence could explained the low titers of induced antibodies. This finding was in line with a preprint result from Chile [ 4 ], reporting that after the CoronaVac vaccination, the SARS-CoV-2 naïve subjects produced lower neutralizing antibody response than the previously seropositive adults. In addition, our finding was supported by other studies [ 1 4 ], reporting that average levels of neutralizing antibodies in the recovered adults were higher than those in CoronaVac-vaccinated healthy adults.…”

What Happens to the Immune System after Vaccination or Recovery from COVID-19?

“…Likewise, Muena et al (2021) studied 27 seropositive individuals who were immunized with the two main vaccines currently being used in Chile: CoronaVac (SinoVac) or BNT162b2 (Pfizer-BioNTech) vaccines [141]. Immunization of previously infected individuals with CoronaVac showed no significant differences in neutralizing antibody (NAb) titres after the first dose or when comparing the first and second doses.…”

Counting on COVID-19 Vaccine: Insights into the Current Strategies, Progress and Future Challenges

“…Comparatively low efficacy of the two-dose schedule of CoronaVac than single dose was doubted to be the result of some non-pharmaceutical interventions or bias in the setting [ 163 ]. Two doses of CoronaVac have been observed to boost longer-lasting neutralizing antibody responses in previously seropositive patients possibly via inducing B cell memory responses [ 281 ]. However, this boosting effect was absent in three patients, obesity being the common factor among them.…”