Background: Vaccination is one of the best ways to control the SARS-CoV-2 outbreak. In Taiwan, healthcare workers were prioritized for vaccination, but the effectiveness of these vaccines for them remains unclear. Thus, it's essential to examine their neutralizing antibodies after prime-boost vaccinations.
Methods: In this prospective observational study, 514 healthcare workers from Chang Gung Memorial hospitals in Taiwan were included between 19 March 2021 and 21 August 2021. The two doses of COVID-19 vaccines were either a match or a mixing of AZD1222 and mRNA-1273, e.g. AZD1222 + AZD1222 (n = 406), mRNA-1273 + mRNA-1273 (n = 62), and AZD1222 + mRNA-1273 (n = 46). Blood specimens were drawn after two doses of vaccines, defined as post-vaccine days [median 34.00 days and interquartile range (IQR) 29.00-42.00 days], and examined for the neutralizing antibodies via SARS-CoV-2 neutralization kits. The results were analyzed as a percentage of inhibition based on the negative control.
Results: After 2 vaccination doses, subjects with AZD1222 + mRNA-1273 (median 97.15%, IQR 96.06-98.06%) and mRNA-1273 + mRNA-1273 (median 97.47%, IQR 96.75-97.89%) exhibited higher neutralizing antibodies than those receiving AZD1222 + AZD1222 vaccines (median 71.28%, IQR 49.39-89.70%) (the percentage was referred to inhibition of surrogate virus). The post-vaccination days negatively impacted the neutralizing antibodies, except for the mRNA-1273 + mRNA-1273 group. The presence of fever, headache, and myalgia after the second dosage was reflected in the higher neutralizing antibodies (median of no fever 76.00% vs. fever 97.00%, p < 0.0001; median of no headache 76.00% vs. headache 95.00%, p < 0.0001; median of no myalgia 75.50% vs. myalgia 96.00%, p < 0.0001). The subjects with underlying diseases, including hypertension and cancer showed lower neutralizing antibodies (median of no hypertension 81.00% vs. hypertension 56.00%, p = 0.0029; median of no cancer 81.00% vs. cancer 56.00%, p = 0.0143).
Conclusion: Heterologous prime-boost vaccines (AZD1222 + mRNA-1273) and two doses of mRNA vaccines are recommended. For future directions, we need to investigate the effectiveness of the vaccination against new SARS-CoV-2 variants.
Keywords: AZD1222; SARS-CoV-2 vaccination; Taiwan healthcare workers; mRNA-1273; neutralizing antibody.
Vaccination with AZD1222 + mRNA-1273 and mRNA-1273 + mRNA-1273 produced higher neutralizing antibodies than AZD1222 + AZD1222 in Taiwan healthcare workers.Neutralizing antibodies were associated with vaccine side effects, including fever, headache, and myalgia.Underlying diseases (hypertension and cancer) and time after vaccinations reduced neutralizing antibodies from the vaccinations.