COVID-19 vaccine effectiveness against severe acute respiratory infections (SARI) hospitalisations associated with laboratory-confirmed SARS-CoV-2 in Ghana, June 2022 to March 2024.

BACKGROUND

The use of vaccines to urgently respond to the COVID-19 pandemic generated the need for monitoring vaccine effectiveness in the context of new viral variants and changing epidemiology. This study measured the COVID-19 vaccine effectiveness (VE) against laboratory-confirmed SARS-CoV-2 in hospitalised patients diagnosed with severe acute respiratory infections (SARI) in Ghana.

METHODS

This was a test-negative, case-control study, among patients aged ≥15 years, attending 32 hospitals that participate in influenza surveillance system between June 2022 and March 2024. Naso-and oropharyngeal swabs were tested for SARS-CoV-2 by PCR. Medical and vaccination data were obtained. VE was estimated as one minus adjusted odds of vaccination among participants, expressed as a percentage, and the reference was either unvaccinated cases (absolute VE) or unvaccinated plus those vaccinated >12 months prior to symptom onset (annual VE).

RESULTS

Of 1974 SARI patients, 1796 (91%) were enrolled, including 929/1796 males (52%) and 867/1796 females (48%); 41% were above 60 years old. At least one chronic medical condition was reported in 167/1796 (9%) participants. A total of 118/1796 (7%) tested positive for SARS-CoV-2, of whom 29 (25%) have received at least one dose of vaccine (Sputnik V, Vaxzevria, JCovden, or Comirnaty). Of the 1678 (93%) who tested negative for SARS-CoV-2, 412 (25%) received at least one dose of vaccine. Among pregnant women (n = 50), 5 (10%) tested positive for SARS-CoV-2 Absolute and annual VE against COVID-19 SARI hospitalization were respectively 22% (95% CI, -107-70) and 19% (95% CI, -113%-50%) for last dose of vaccine received up to 179 days prior but waned after 6 months.

CONCLUSION

COVID-19 vaccines may have prevented COVID-19-associated SARI hospitalizations in the first 6 months over the study period in Ghana, and a pattern of protective effective was observed, consistent with report from other settings, although effect estimates were imprecise.