ABSTRACT
Background COVID-19 vaccines with alternative strain compositions are needed to provide broad protection against newly emergent SARS-CoV-2 variants of concern. Methods We conducted a global Phase 3, multi-stage efficacy study (NCT04904549) among adults aged [≥]18 years. Participants were randomized 1:1 to receive two intramuscular injections 21 days apart of a bivalent SARS-CoV-2 recombinant protein vaccine with AS03-adjuvant (5 g of ancestral (D614) and 5 g of B.1.351 [beta] variant spike protein) or placebo. Symptomatic COVID-19 was defined as laboratory-confirmed COVID-19 with COVID-19-like illness (CLI) symptoms. The primary efficacy endpoint was the prevention of symptomatic COVID-19 [≥]14 days after the second injection. Results Between 19 Oct 2021 and 15 Feb 2022, 12,924 participants received [≥]1 study injection. 75% of participants were SARS-CoV-2 non-naive. 11,416 participants received both study injections (efficacy-evaluable population [vaccine, n=5,736; placebo, n=5,680]). Up to 15 March 2022, 121 symptomatic COVID-19 cases were reported (32 in the vaccine group and 89 in the placebo group) [≥]14 days after the second injection with a vaccine efficacy (VE) of 64.7% (95% confidence interval [CI] 46.6; 77.2%). VE was 75.1% (95% CI 56.3; 86.6%) in non-naive and 30.9% (95% CI -39.3; 66.7%) in naive participants. Viral genome sequencing identified the infecting strain in 68 cases (Omicron [BA.1 and BA.2 subvariants]: 63; Delta: 4; Omicron and Delta: 1). The vaccine was well-tolerated and had an acceptable safety profile. Conclusions A bivalent vaccine conferred heterologous protection against symptomatic infection with newly emergent Omicron (BA.1 and BA.2) in non-naive adults 18-59 years of age. ClinicalTrials.gov: NCT04904549
ABSTRACT
The African continent has some of the worlds lowest COVID-19 vaccination rates. While the limited availability of vaccines is a contributing factor, COVID-19 vaccine hesitancy among health care providers (HCP) is another factor that could adversely affect efforts to control infections on the continent. We sought to understand the extent of COVID-19 vaccine hesitancy among HCP, and its contributing factors in Africa. We evaluated COVID-19 vaccine hesitancy among 1,499 HCP enrolled in a repeated cross-sectional telephone survey in Burkina Faso, Ethiopia, Nigeria, Tanzania and Ghana. We defined COVID-19 vaccine hesitancy among HCP as self-reported responses of definitely not, maybe, unsure, or undecided on whether to get the COVID-19 vaccine, compared to definitely getting the vaccine. We used Poisson regression models to evaluate factors influencing vaccine hesitancy among HCP. Approximately 65.6% were nurses and the mean age ({+/-}SD) of participants was 35.8 ({+/-}9.7) years. At least 67% of the HCP reported being vaccinated. Reasons for low COVID-19 vaccine uptake included concern about vaccine effectiveness, side effects and fear of receiving unsafe and experimental vaccines. COVID-19 vaccine hesitancy affected 45.7% of the HCP in Burkina Faso, 25.7% in Tanzania, 9.8% in Ethiopia, 9% in Ghana and 8.1% in Nigeria. Respondents reporting that COVID-19 vaccines are very effective (RR:0.21, 95% CI:0.08, 0.55), and older HCP (45 or older vs.20-29 years, RR:0.65, 95% CI: 0.44,0.95) were less likely to be vaccine-hesitant. Nurses were more likely to be vaccine-hesitant (RR 1.38, 95% CI: 1.00,1.89) compared to doctors. We found higher vaccine hesitancy among HCP in Burkina Faso and Tanzania. Information asymmetry among HCP, beliefs about vaccine effectiveness and the endorsement of vaccines by the public health institutions may be important. Efforts to address hesitancy should address information and knowledge gaps among different cadres of HCP and should be coupled with efforts to increase vaccine supply.
ABSTRACT
COVID-19 vaccine hesitancy among adolescents poses a challenge to the global effort to control the pandemic. This multi-country survey aimed to assess the levels and determinants of COVID-19 vaccine hesitancy among adolescents in sub-Saharan Africa between July and December 2021. The survey was conducted using computer-assisted telephone interviewing among adolescents in five sub-Saharan African countries, Burkina Faso, Ethiopia, Ghana, Nigeria, and Tanzania. A rural area and an urban area were included in each country (except Ghana, which only had a rural area), with approximately 300 adolescents in each area and 2803 in total. Sociodemographic characteristics and perceptions and attitudes on COVID-19 vaccines were measured. Vaccine hesitancy was defined as definitely not getting vaccinated or being undecided on whether to get vaccinated if a COVID-19 vaccine were available. Log-binomial models were used to calculate the adjusted prevalence ratios (aPRs) and 95% confidence intervals (CIs) for associations between potential determinants and COVID-19 vaccine hesitancy. The percentage of COVID-19 vaccine hesitancy was 15% in rural Kersa, 24% in rural Ibadan, 31% in rural Nouna, 33% in urban Ouagadougou, 37% in urban Addis Ababa, 48% in rural Kintampo, 64% in urban Lagos, 76% in urban Dar es Salaam, and 88% in rural Dodoma. Perceived low necessity, concerns about vaccine safety, and concerns about vaccine effectiveness were the leading reasons for hesitancy. Healthcare workers, parents or family members, and schoolteachers had the greatest impacts on vaccine willingness. Perceived lack of safety (aPR: 3.61; 95% CI: 3.10, 4.22) and lack of effectiveness (aPR: 3.59; 95% CI: 3.09, 4.18) were associated with greater vaccine hesitancy. The levels of COVID-19 vaccine hesitancy among adolescents are alarmingly high across the five sub-Saharan African countries, especially in Tanzania. COVID-19 vaccination campaigns among sub-Saharan African adolescents should address their concerns and misconceptions about vaccine safety and effectiveness.
