Assessment of long-term adverse events regarding different COVID-19 vaccine regimens within an 18-month follow-up study.

Early reports on coronavirus disease 2019 (COVID-19) vaccines presented the short-term adverse events (AEs). This follow-up study investigated a standard regimen based on protein subunit vaccines, PastoCovac and PastoCovac Plus, and the combinational vaccine regimens including AstraZeneca/PastoCovac Plus and Sinopharm/PastoCovac Plus. The participants were followed up to 6 months post the booster shot. All the AEs were collected through in-depth interviews using a valid researcher-made questionnaire and were evaluated regarding the association with the vaccines. Of the 509 individuals, 6.2% of the combinational vaccine participants had late AEs, of whom 3.3% suffered from cutaneous manifestations, followed by 1.1% arthralgia complaints, 1.1% with neurologic disorders, 0.3% ocular problems and 0.3% metabolic complications, with no significant difference between the vaccine regimens. For the standard regimen, 2% of the individuals experienced late AEs as (1%), neurological disorders (0.3%), metabolic problems (0.3%) and involvement of joints (0.3%). Notably, 75% of the AEs were persistent up to the end of the study. A low number of late AEs were captured in 18 months as 12 improbable, 5 unclassifiable, 4 possible and 3 probable associated AEs with the vaccine regimens. The benefits of COVID-19 vaccination far exceed the potential risks and late AEs seem to be uncommon.

PastoCovac and PastoCovac Plus as protein subunit COVID-19 vaccines led to great humoral immune responses in BBIP-CorV immunized individuals.

The optimal booster vaccine schedule against COVID-19 is still being explored. The present study aimed at assessment of the immunogenicity and antibody persistency of inactivated-virus based vaccine, BBIP-CorV and protein-subunit based vaccines, PastoCovac/Plus through heterologous and homologous prime-boost vaccination. Totally, 214 individuals who were previously primed with BBIBP-CorV vaccines were divided into three arms on their choice as heterologous regimens BBIBP-CorV/PastoCovac (n = 68), BBIBP-CorV/PastoCovac Plus (n = 72) and homologous BBIBP-CorV (n = 74). PastoCovac booster recipients achieved the highest rate of anti-Spike IgG titer rise with a fourfold rise in 50% of the group. Anti-RBD IgG and neutralizing antibody mean rise and fold rise were almost similar between the PastoCovac and PastoCovac Plus booster receivers. The antibody durability results indicated that the generated antibodies were persistent until day 180 in all three groups. Nevertheless, a higher rate of antibody titer was seen in the heterologous regimen compared to BBIP-CorV group. Furthermore, no serious adverse event was recorded. The protein subunit-based booster led to a stronger humoral immune response in comparison with the BBIP-CorV booster receivers. Both the protein subunit boosters neutralized SARS-CoV-2 significantly more than BBIP-CorV. Notably, PastoCovac protein subunit-based vaccine could be successfully applied as a booster with convenient immunogenicity and safety profile.