A new study has revealed that vaccines are most effective four to five months after receiving double doses – but is more effective for the Alpha variant compared to the Delta.
With cases and deaths increasing across the UK and winter approaching, talks are currently taking place about the potential need for a booster vaccine campaign in order to to improve the country’s overall immunisation to the virus.
What does the study reveal?
Led by Oxford University and the Office for National Statistics, the study was based on two and a half million tests results from 743,526 participants in the UK’s Covid-19 household-infection survey.
When comparing Pfizer/BioNTech’s and Oxford/AstraZeneca vaccines, data reveals that the Oxford/AstraZeneca jab offers the same level of high protection as the Pfizer/BioNTech. However, the Pfizer/BioNTech vaccine had 93 per effectiveness against symptomatic infection two weeks after the second dose, compared with Oxford/AstraZeneca’s 71 per cent.
Over time, however, the Pfizer/BioNTech’s effectiveness dropped while Oxford/AstraZeneca’s remained largely the same.
The study also pointed to the lower effectiveness of vaccines on the Delta variant, revealing that those double vaccinated who subsequently become infected with the variant have similar levels of the virus to those unvaccinated.
This contrasts with the initial Alpha variant, where viral loads were much lower in those double vaccinated.
Other key points from the research include:
- People who have had Covid-19 gain even more antibodies when fully vaccinated
- The time between first and second doses does not affect the vaccines’ effectiveness
- Younger people gain more protection from vaccination than older
What does this all mean?
Professor Walker said: ”We don’t yet know how much transmission can happen from people who get Covid-19 after being vaccinated.
“For example, they may have high levels of virus for shorter periods of time.
“But the fact that they can have high levels of virus suggests that people who aren’t yet vaccinated may not be as protected from the Delta variant as we hoped.
“This means it is essential for as many people as possible to get vaccinated – both in the UK and worldwide.”
What happens next?
The Joint Committee on Vaccination and Immunisation (JCVI) met on Thursday to discuss the possible need for a booster campaign and wider rollout, to improve the immunisation of people against the Delta variant.
Professor Adam Finn, a professor in paediatrics at the University of Bristol said those who are “very unlikely to be well protected by those first two doses” will need to receive a third.
Support for a wider rollout is being backed by another Government adviser, Professor Peter Openshaw, who said further evidence is needed on any benefits booster jabs might bring.
What is the concern?
Government announced on Wednesday that 111 people have died within 28 days of testing positive for Covid-19, while cases stood at 33,904 lab-confirmed cases in the UK.
The latest Test and Trace statistics showed 190,508 people tested positive for Covid-19 at least once in the week to August 11, up 6 per cent from the previous week
Prof Openshaw, a member of the New and Emerging Respiratory Virus Threats Advisory Group (Nervtag) which advises the Government, responded to the growing numbers of cases and deaths as “very worrying”, warning that “we just don’t really know what’s going to happen”.
With winter approaching and children scheduled to return to school in September, Prof Openshaw told Times Radio: “I think it’s very worrying. This is a very large number. If you think, 34,000 people, that’s a lot of people testing positive, and to be seeing over 100 deaths a day at this stage, you know before schools have gone back, while the weather is still relatively good, we’re not back into winter yet.
“I think we’re all really anxious about what’s going to happen once we return to normality.”
He added: “We’re going into the winter with really very high levels of infection out there in the community and we just don’t really know what’s going to happen.”
Health Secretary Sajid Javid has touched on the need for a booster campaign which, if advised by clinical experts, will begin from September.
