The effectiveness of COVID-19 Heterologous Vaccination: the experience from a Regional Hospital in Cameroon

Background: With most COVID-19 vaccines requiring at least 2 doses, heterologous vaccination will facilitate vaccination programs where vaccine supplies fluctuate. However, with insufficient data on effects of heterologous vaccination in our setting, people remain reluctant to mix. Objectives: We seek to assess the effects of heterologous vaccination on morbidity and mortality. Methods: This was a 7 months retrospective study for COVID-19 patients managed by the Bamenda Regional Hospital, Cameroon, running from the 18th August 2021 to 28th February 2022. Logistic regression used to asses relationship between predictors and outcome. Results: Our 1254 participants had a mean age of 50.1(±19.6) years, we had 24 (1.9%) being fully vaccinated, where 7 (29.2%) took heterologous vaccines. Also, 721 (57.5%) had the moderate/severe form of the disease. Those fully vaccinated had lower odds of having severe disease (p=0.037). However, heterologous vaccination compared to homologous vaccination had no significant difference on morbidity (p=0.729). Among patients who died, none was fully vaccinated. Conclusion: The protective effect of vaccination on morbidity was similar in those with heterologous vaccination as well as those who took Keywords: COVID-19 vaccine; heterologous vaccination; homologous vaccination.