This website is intended for healthcare professionals only.
Take a look at a selection of our recent media coverage:
13th December 2021
In a press release, Pfizer and BioNTech have announced that serum antibodies induced after three doses of their COVID-19 vaccine (BNT162b2) are able to neutralise the Omicron variant.
The company’s laboratory study involved testing human sera obtained from the blood of individuals who had received two or three 30-µg doses of the BNT162B2 using a pseudovirus neutralisation test, which used to study the effect of antibodies to neutralise the capability of viruses to enter cells and thus prevent infection. The sera were collected from subjects 3 weeks after receiving the second dose or one month after receiving the third dose of their vaccine
In the study, each sample of serum was simultaneously tested for its neutralising antibody titre against the original (or wild-type) COVID-19 spike protein as well as the Omicron spike variant. The researchers found that after a third vaccine dose, there was a significant, 25-fold increased level of neutralising antibody titres against the Omicron strain spike protein. In fact, antibody titre levels against the Omicron variant were comparable to the neutralisation against the wild-type strain observed in sera from individuals who received two doses of the companies’ COVID-19 vaccine. However, data on the persistence of these neutralising antibodies over time is uncertain and will be determined over time.
At the present time, there is still much to learn about the Omicron variant although a preliminary study from South Africa in 12 people has provided some answers. The study included 12 individuals with a mean age of 57 years (66% male), 6 of whom had been vaccinated with the remaining 6 having been both vaccinated and previously infected. The purpose of the study was to examine whether the Omicron variant still required the ACE2 receptor to gain entry to cells and if plasma from those vaccinated with BNT162b2 were able to neutralise the variant. The results showed that the ACE2 receptor was still required to gain entry to cells but also that there was a 41-fold reduction in antibody neutralisation against Omicron compared with the original wild-type. However, on the plus side, escape was much less in those who had been previously infected the COVID-19.
There is still much to learn about the Omicron variant, in particular its transmissibility and whether it results in more severe infections and hospitalisations.
However, one point reassuring point mentioned in Pfizer-BioNTech press release was how 80% of the regions of the spike protein that are recognised by cytotoxic (killer) T (CD8 +) cells are unchanged in the variant. It is possible therefore, that three doses, i.e., full vaccination and a booster, will hopefully provide an enhanced immune response and which may be sufficient to prevent the variant from causing more severe disease.
6th December 2021
A Comirnaty booster dose in those over the age of 50 provides a greater than 90% vaccine effectiveness, irrespective of whether individuals had been previously fully vaccinated with ChAdOx1-S (AstraZeneca) or Comirnaty (BNT162b). This was the finding of a study by a team from the UK Health Security Agency, UK, which is available online but not published in a peer-reviewed journal.
With evidence that the efficacy of COVID-19 vaccines wanes 20 weeks after vaccination, the Joint Committee on Vaccination and Immunisation (JCVI) in the UK issued a statement highlighting the need for a booster dose of COVID-19 vaccines in an effort to combat the virus during the winter months. Moreover, after a review of the available data on booster responses, the JCVI advised a preference for the Comirnaty vaccine as the booster dose irrespective of which product was used to provide the initial full vaccination.
In the present study, the UK team sought to estimate the real-world effectiveness of a single Comirnaty booster dose in those aged 50 years and older. The researchers compared vaccination status in this patient cohort, who were symptomatic for COVID-19 and with a positive PCR test result. Data was obtained from the National Immunisation Management System (NIMS) and a booster dose was defined as one given 140 days or more after a second vaccination dose. Vaccine effectiveness was adjusted in regression models for age, deprivation, ethnicity, care home residence status and co-morbidities. The analysis was also stratified by the primary vaccination received, i.e., either ChAdOx1-S (AstraZeneca) or Comirnaty and vaccine effectiveness assessed at several time points e.g., 2 to 6 days post booster dose and 14 or more days later.
For the primary analysis, the team compared vaccine effectiveness in those who received a booster with those who had been fully vaccinated but without a booster dose. In a secondary analysis, they determined the absolute vaccine effectiveness which was the difference in rates of infection between those who had two doses (at least 140 days apart) and a booster with those who were unvaccinated.
There were 271,747 eligible tests in people 50 years and older, of which 13,568 (5%) were unvaccinated with the remainder being fully vaccinated with either ChAdOx1-S or comirnaty (BNT162b)
The vaccine effectiveness from a BNT162b booster in those who were fully vaccinated with ChAdOx1-S was 87.4% (95% CI 84.9 – 89.4) and 84.4% (95% CI 82.8 – 85.8%) in those fully vaccinated with BNT162b.
In the secondary analysis, compared with unvaccinated individuals, those fully vaccinated with a primary course of ChAdOx1-S had an absolute vaccine effectiveness of 93.1% (95% CI 91.7 – 94.3%) and 94% (95% CI 93.4 – 94.6%) in those fully vaccinated with BNT162b.
Interestingly, when compared with those who were fully vaccinated but had not received a booster dose, the vaccine effectiveness after 20 or more weeks was 44.1% for the ChAdOx1-S vaccine and 62.5% for BNT162b.
In their conclusion, the authors wrote ‘our study provides real world evidence of significant increased protection from the booster dose against symptomatic disease in those aged over 50 years of age irrespective of which primary course was received.’
11th October 2021
In the first clinical trial, the BNT162b COVID-19 vaccine was shown to provide 95% protection against COVID-19 in those 16 years of age and older. In addition, a real-world study has confirmed the efficacy observed in the trial, with two doses of BNT162b2 being highly effective in preventing both symptomatic and asymptomatic infections, COVID-19-related hospitalisations, severe disease and death. However, there have been concerns that approved COVID-19 vaccines might show reduced efficacy over time prompting the need for a booster dose.
In an attempt to provide answers as to whether vaccine efficacy wanes over time, a team from the Department of Research and Evaluation, Kaiser Permanente, California, USA, undertook a retrospective cohort study. The team analysed electronic health records for individuals 12 years and older to assess BNT162b effectiveness against COVID-19 infection and related hospitalisations for up to six months. The study outcomes were COVID-19 infections (based on a positive PCR test) and COVID-19-related hospitalisations over a 6 month period.
A total of 3,436,957 individuals with a median age of 45 years (52.4% female) were included in the final analysis. There were 184 041 (5·4%) participants infected with COVID-19, of whom, 12130 (6·6%) were admitted to hospital. Among those fully vaccinated, the vaccine efficacy against infection was 73% (95% CI 72 – 74) and against hospital admission 90% (95% CI 89 – 92). Over a period of 5 months however, vaccine efficacy against infection reduced from 88% (in the first month) to 47% after 5 months. Despite this, vaccine efficacy against hospitalisation remained stable over the study period.
The study also examined vaccine efficacy against the COVID-19 delta variant and 4 months after full vaccination, vaccine effectiveness against this variant declined from 93% to 53%.
The authors concluded that their findings underscored the importance of monitoring vaccine efficacy over time and suggested that a booster dose might be needed to restore high levels of protection.