Factors Influencing the Efficacy of COVID-19 Vaccines: A Quantitative Synthesis of Phase III Trials

Abstract

To date, there is still a paucity of data from Phase III trials concerning the efficacy of vaccines against COVID-19. Furthermore, no studies investigated the variables that may modulate the efficacy of vaccination. The aim of this analysis was to assess whether there are modifying factors that may potentially influence the clinical efficacy of COVID-19 vaccines. A quantitative synthesis of data from Phase III trials was performed via pairwise and network meta-analyses, along with meta-regression analysis. Data from Phase III trials are currently available only for AZD1222, BNT162b2, mRNA-1237, and Sputnik V. Vaccination resulted to be generally effective (90.0%, 95%CI 72.6–96.4; p < 0.001), although the efficacy of AZD1222 (62.1%) introduced a significant level of heterogeneity in the meta-analysis (I2 92.17%, p < 0.001). No significant modifying factors resulted from the meta-regression analysis. However, considering the mRNA-based vaccines, a trend toward significance (p = 0.081) resulted for age. The network meta-analysis provided the following rank of effectiveness: BNT162b2 ≃ mRNA-1273 > Sputnik V >> AZD1222. In conclusion, no modifying factors seem to modulate the efficacy of vaccines against COVID-19. This quantitative synthesis will need to be updated as soon as further clinical results on the efficacy profile are available from Phase III trials for further licensed COVID-19 vaccines.

Predicted antiviral drugs Darunavir, Amprenavir, Rimantadine and Saquinavir can potentially bind to neutralize SARS-CoV-2 conserved proteins

“…Using anti-viral drug has great advantage in that these have specific target and less or no similar binding partners like Rimantadine had no other binding partners other than SARS-Cov-2 NSPs (Tables 1 , 2 , 3 , 4 , 5 , 6 , 7 , 8 , 9 , 10 and 11 ). Finally, these predicted drug combinations must be clinically tested to save thousands of lives in the vicinity of limited effectiveness of developed vaccines [ 58 , 59 ].…”

Potential Therapeutic Targets and Vaccine Development for SARS-CoV-2/COVID-19 Pandemic Management: A Review on the Recent Update

“…The vaccine showed 72% overall efficacy and 86% efficacy against severe disease in the U.S. The protection starts around 14 days after vaccination but it is not known how long protection continues ( 237 , 238 ). In contrast to the Pfizer and Moderna vaccines, this vaccine is easier to store and only includes a single dose, which simplifies distribution and administration.…”

“…All six cases were among women aged between 18 and 48, and the single-dose vaccine occurred six to 13 days after receiving it. These six instances were exceptionally uncommon, occurring in the course of over seven million doses given ( 237 , 238 ). The number of cases has since increased, and it is too soon to tell what the prevalence of VITT will be ultimately.…”

“…The second dose is of the Ad5 serotype, which stimulates the body to develop a stronger immune response. Heterological vaccination can be a reasonable choice for antagonizing the harmful consequences of the immune reaction to vaccine vectors ( 237 , 238 ). The Lancet published the Phase III results showing a 91.6 percent efficacy against the virus’s initial strain on February 2, 2021.…”

“…Following the launch of Sputnik-V, the Russian government issued provisional requests from 20 countries for more than 1 billion doses of Sputnik V vaccine ( Figure 13 ). Russia is now producing over 500 million doses of the Sputnik V vaccine ( 237 , 238 ).…”