Efficacy of the modified vaccinia Ankara virus vaccine and the replication-competent vaccine ACAM2000 in monkeypox prevention

BACKGROUND: Recently, there has been an uptick in reported cases of monkeypox (Mpox) in Africa and across the globe. This prompted us to investigate the efficacy of the two vaccines that can prevent Mpox, the modified vaccinia Ankara virus (MVA) vaccine and ACAM2000 vaccine. We analyzed them to determine their rates of humoral cell responses, adverse events, and rash reactions and used these factors as the primary indicators. METHODS: This study adapted primary data obtained from the Medline, Google Scholar, and Cochrane Library databases. We included a total of eight studies, three of which explored the ACAM2000 vaccine and five of which explored the JYNNEOS MVA vaccine. RESULTS: There were significant differences in the rates of humoral responses after inoculation by the two vaccines. JYNNEOS MVA vaccine immunization resulted in a statistically significant increased humoral immune response with an effect size of 81.00 (42.80, 119.21) at a 95% CI and a rash reaction with an effect size of 96.50 (42.09, 235.09.21) at a 95% CI. ACAM2000 resulted in a lesser increase in neutralizing antibodies than JYNNEOS MVA vaccine. Similar findings were identified for the rates of adverse reactions, but the difference was not statistically significant. The differences in rash reaction rates in the two vaccination groups were also not statistically significant. CONCLUSION: ACAM2000 and JYNNEOS vaccines have proven to be efficient in preventing Mpox even though variations exist in their modes of action and associated significant effects. The nonreplicating nature of JYNNEOS prevents the occurrence of the adverse effects seen with other vaccines.