Characterizing Covid 19 Breakthrough Infections in Manicaland Province, Zimbabwe

Abstract

COVID-19 has caused significant morbidity and mortality as-well as marked deterioration in economies, social relationships and educational systems. All these reasons have fueled the urgent need to develop safe and effective vaccines. Over 7 billion doses of COVID -19 vaccines have been administered globally, however, COVID-19 infections have been reported in fully vaccinated individuals. 16% of cases reported in Manicaland between 6 April and 31 December 2021 were in vaccinated individuals as such this study’s aim was to determine the factors associated with Covid-19 breakthrough infections in Manicaland. A mixed methods approach utilizing both qualitative and quantitative methods was used. Secondary data analysis was done through an unmatched 1:1 case control study. A total of 4 838 study participants (2 420 cases and 2 418 controls) were included in the study. Controls were randomly selected from the Covid-19 vaccine registry while cases where sampled from the Covid-19 line list using the census method. Case were defined as a symptomatic or asymptomatic individual residing in Manicaland aged 18 years and older who received 2 doses of either Sinopharm or Sinovac and tested positive for Covid-19.The results showed that Covid-19 breakthrough infection in Manicaland were more common in males (53.1%) and affected individuals had a median age of 39 years. There was no significant association between breakthrough infections and gender (p = 0.326) as-well as having a comorbidity (p=0.473). There were five common symptoms amongst cases, however cough was the most common and present in 33.7%. Vaccine type was significantly associated with having a breakthrough infection (OR= 0.7, 95%CI: 0.6 – 0.8, p <0.001). Sinovac recipients were 30% less likely to get a breakthrough infection. History of contact was also significantly associated with breakthrough infections (OR= 7.6, 95%CI: 4.8 – 12.0, p< 0.001). Reviews of the line list revealed over 60 variables on the list with age and gender being some of the variable with a high degree of completeness. However, 76.8% of cases had missing data on comorbidities and 64.1% had no disease outcomes. There is need to encourage people to continue observing Covid-19 prevention strategies even if they are fully vaccinated. There is an urgent need to review the current Covid line list, standardise formats and terms as-well as training the users.