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14th November 2022
Vaccine confidence has reduced compared to pre-pandemic levels, according to the findings of a recent, repeated public survey by researchers from the School of Biological Sciences, University of Portsmouth, UK.
The World Health Organisation describes immunisation as a global health and development success story. In 2020, the development of a vaccine against COVID-19 occurred very rapidly yet previously, the fastest vaccine development from viral sampling to approval had been four years, for mumps in the 1960s. Patient’s reluctance to receive vaccination, i.e., vaccine hesitancy is influenced by several factors, with a 2021 narrative review finding that COVID-19 vaccine acceptance ranged from 77.6% in the general population to 86.1% among students. A further factor affecting vaccine hesitancy is what might be termed ‘vaccine confidence’ and which has been largely driven by the rapidity of vaccine development and subsequent uncertainties over safety.
In November/December 2019 when the first cases of infection were being reported in China, the UK researchers undertook a patient survey and which was repeated in January/February 2022. In light of the pandemic, the most recent iteration of the survey was modified to include two questions: one on the number of vaccines individuals had received and the second, enquiring about an individual’s confidence in vaccines (whether it had increased/stayed the same/decreased) since the pandemic. For the survey, the researched calculated a vaccine confidence score (VCS) which was compared between the two surveys.
Vaccine confidence score change over time
The original 2019 survey included 739 participants (19.6% male) and of whom, 45.5% were aged 18 – 24 and only 4.2% aged 60 years and over. For the 2022 survey, a total of 270 respondents (27.8% male) were included but this time, the majority (68.8%) were in the 18 to 24 age range and only 3.4% were aged 60 years and older.
The median VCS in 2019 was 22 and significantly reduced to 20 in the follow-up survey (p = 0.001) with lower values seen across all age groups, between the sexes and based on graduate status.
In contrast however, the 2022 survey observed a significant association between the number of COVID-19 vaccines received and vaccine confidence score, which became higher as the number of doses received increased.
Finally, in the 2022 survey, 23.8% of respondents stated that their confidence in vaccines had decreased compared to 21.6% who stated that confidence had increased, whereas it remained unchanged at 54.6%.
The authors concluded that despite the success of the COVID-19 vaccination program, vaccine confidence had significantly declined since the onset of the pandemic.
Siani A et al. Is vaccine confidence an unexpected victim of the COVID-19 pandemic? Vaccine 2022
6th January 2021
The first vaccine to achieve regulatory approval in the UK was the BNT162b2 vaccine produced by US manufacturer, Pfizer in conjunction with BioNTech, who manufactured the vaccine.
In this Phase III study, participants were randomised on a 1:1 basis to receive either BNT162b2 or placebo, which was a saline solution. The trial included healthy participants 16 years and over although those with a stable chronic medical condition were also recruited. In contrast, participants receiving treatment for immunosuppressive therapy or with a diagnosis for an immunocompromising condition were excluded. The primary end point was the efficacy of BNT162b2 against confirmed cases of COVID-19 that occurred at least 7 days after the second dose, among participants who, up until this time point, were free of infection. Confirmation of infection was via PCR testing and the presence of at least one recognised symptom, e.g., fever, new/increased cough etc. The vaccine efficacy was calculated as 100 x (1 – IRR) where IRR was the ratio of confirmed cases in BNT162b2 per 1000 person-years compared to the cases in the placebo group. A secondary endpoint was the efficacy against severe COVID-19 which was defined by additional features such as severe systemic illness, respiratory failure, admission to an intensive care unit.
A total of 43,548 participants were enrolled in the study with a median age of 52 years and an equal sex distribution and randomised to BNT162b2 or placebo. Among 36,523 participants without evidence of COVID-19, there were 8 confirmed cases among vaccine recipients and 162 among those given the placebo, which corresponded to a vaccine efficacy of 95%. The study also found that between the first and second vaccine doses, there were 39 positive cases among vaccine recipients and 82 in the placebo group, giving an efficacy of 52%. These data suggested that the vaccine offered early protection, which the authors reported was as soon as 12 days after the first dose. Among patients who developed severe disease, there was one case after the first dose of BNT162b2 and 9 after the placebo. Safety assessments noted mild to moderate injection site pain, fatigue and headache although the incidence of serious incidents was low (< 2%). The authors also reported that participants will continue to be followed for up to 2 years after the second vaccine dose.
Pollack FP et al. Safety and efficacy of the BNT162b2 mRNA covid-19 vaccine. N Engl J Med 2020 doi 10.1056/NEJMoa2034577