ABSTRACT
AIMS: Despite high vaccination rates, increasing case numbers continue to be reported with the identification of new variants of concern, and the issue of durability of the vaccine-induced immune response remains hot topic. Real-life data regarding time-dependent immunogenicity of inactivated COVID-19 vaccines are scarce. We aimed to investigate the changes in the antibody at the different times after the second dose of the CoronaVac vaccine. METHODS: The study included 175 HCWs vaccinated with inactive CoronaVac (Sinovac Life Sciences, China) SARS-CoV-2 vaccine in two doses. Anti-spike/RBD IgG levels were measured first, third, and sixth months after the second dose. Chemiluminescent microparticle immunoassay (IgG II Quant test, Abbott, USA), which is 100% compatible with plaque reduction neutralization test, was used. RESULTS: Mean age of the participants was 38 ± 11.23 years (range between 22 and 66) of whom 119 (63.9%) were female, and 56 (32%) were male. Dramatic reductions were demonstrated in median antibody levels particularly in the infection-naïve group, comprising 138 HCWs compared to those with prior history of COVID-19 infection (n = 37) (p < 0.001). There was no difference between the two groups in terms of age, gender, blood groups, BMI, and comorbid diseases. CONCLUSIONS: While antibody positivity remained above 90% in the 6th month after two doses of inactivated vaccine in HCWs, the median titers of neutralizing antibodies decreased rapidly. The decrease was more rapid and significant in those with no history of prior COVID-19 infection. In this critical phase of the pandemic, where we are facing the dominance of the Omicron variant after Delta, booster doses have become vital.
ABSTRACT
BACKGROUND AND OBJECTIVES: Healthcare workers (HCWs) were among the first groups to be vaccinated in Turkey. The data to be obtained by the vaccination of HCWs would guide wide spread vaccination programs. MATERIALS AND METHODS: The study included 330 HCWs working at Istanbul University-Cerrahpasa, Cerrahpasa Medical Faculty Hospital and vaccinated with inactive CoronaVac (Sinovac Life Sciences, China) SARS-CoV-2 vaccine in two doses (28 days apart). Anti-Spike /RBD IgG levels were measured 14 days after the first dose and 28 days after the second dose. Chemiluminescent microparticle immunoassay (CMIA) (ARCHITECT IgG II Quant test, Abbott, USA), which is 100% compatible with plaque reduction neutralization test (PRNT), was used. RESULTS: Of the participants, 211 (63.9%) were female, 119 (36.1%) were male, and mean age was 39.6 ± 7.7 years. In those without prior COVID-19 history; (n = 255) antibody positivity was detected as 48.2% (95% CI: 42.1-54.3) 14 days after the first dose of vaccine, and 99.2% (95% CI: 98.1-100) at day 28 after the second dose. Antibody titers were significantly lower in patients with hypertension (p = 0.011). In those with prior history of COVID-19 (n = 75); both the antibody positivity rates after the first vaccine (48.2% vs 100%, p = 0.000) and the anti-spike/RBD antibody levels after the second vaccine (with a ≥ 1050 AU/mL titer equivalent to PRNT 1/80 dilution) was significant than infection-naive group (25.9% vs. 54.7%, p = 0.000). Antibody positivity after two doses of vaccination for all study group was 99.4% (95% CI: 98.6-100). CONCLUSIONS: Two doses CoronaVac produce effective humoral immunity in HCWs. Antibody response is significantly higher in those with prior history of COVID-19 than infection-naive group. Given no significant benefit of the second dose, a single shot of vaccination may be sufficient for those with prior history of COVID-19. Monitoring humoral and cellular immune responses, considering new variants, is required to validate this approach.
Subject(s)
COVID-19 Vaccines , COVID-19 , Adult , Antibodies, Viral , Antibody Formation , Female , Health Personnel , Humans , Male , Middle Aged , SARS-CoV-2ABSTRACT
The COVID-19 pandemic continues to be a major health problem worldwide. Timely diagnosis of co-infections mimicking COVID-19, such as malaria, might be challenging particularly in non-endemic areas. We report the first case of COVID-19 and Plasmodium ovale malaria co-infection from our region aiming to highligt the importance of travel history and prophylaxis in malaria management in the context of pandemic. The galloping sound can sometimes be a harbinger of zebra besides the horse.