WITH the emergence of new variants in the UK, Brits will are curious about how much protection their jab offers them.
The vaccines were created against the original coronavirus strain from Wuhan, China.
They have shown huge success rates for preventing severe disease and death, already preventing 13,000 deaths in the UK.
But when the virus evolves, sometimes it develops mutations which make vaccines weaker.
The immune system – trained against the old virus strain – may fail to produce enough antibodies.
But generally speaking, althought some variants have “escape mutations”, there is confidence the jabs will prevent hospitalisations and deaths.
There are three jabs being given out in the UK – Pfizer, AstraZeneca and Moderna. Each require two doses.
So how much immunity do you have once fully vaccinated?
How effective is the Pfizer vaccine?
The Pfizer/BioNTech jab has wowed scientists at how effective it is, with the clinical results coming out at the end of 2020.
Trials showed that against the original coronavirus strain, it was up to 95 per cent effective at preventing symptomatic disease after the second dose.
Real-world data has continued to support this; a study in Israel, published in May, showed that two doses can provide more than 95 per cent protection against infection, severe illness, and death.
There is a high degree of confidence the Pfizer jab protects against the Kent variant.
A study from Public Health England, published this weekend, said two doses offer 93 per cent protection against symptomatic disease.
The PHE study said the Pfizer vaccine is 88 per cent effective against symptomatic disease caused by the Indian strain after two doses, and only 33 per cent after one.
Experts said it highlighted the importance of getting two doses of your jab.
South African variant
Pfizer claimed in April its vaccine appears to offer 100 per cent protection against the South African variant.
Among 800 people in South Africa, nine cases of the South African variant of Covid were observed – all in the group not given the vaccine.
But experts said the study, published in the Lancet, was on a very small group of people.
An earlier study in February, published in The New England Journal of Medicine, found the jab offered around two-thirds less antibody protection against the South African variant.
Another study found the Pfizer vaccine produces an “off the scale” immune response that is likely to protect against the Brazilian variant.
How effective is the AstraZeneca vaccine?
Studies of the AstraZeneca jab paint a complex picture.
The overall efficacy from the clinical trials of the AstraZeneca jab was put at 70 per cent in December 2020.
After more analysis in March, AstraZeneca said vaccine efficacy was 76 per cent after one dose.
With a gap of 12 weeks or more between the first and second dose, the vaccine efficacy increased to 82 per cent.
This compared to 55 per cent for a six-week interval, according to the University of Oxford research published in The Lancet in February.
The data supported the UK’s strategy to delay the second dose by 12 weeks.
Oxford University researchers also said the jab has a similar efficacy against the Kent variant.
Their study found vaccine efficacy against symptomatic disease was 74.6 per cent against the Kent variant compared to the 84 per cent against other strains.
The AstraZeneca vaccine has been shown to be less effective than Pfizer’s against the Indian variant.
It was 60 per cent effective at cutting cases of symptomatic Covid.
South African variant
A small study in South Africa suggested the Oxford/AstraZeneca vaccine was not effective against mild illness caused by the variant discovered there.
Oxford University said the study did not assess protection against moderate to severe disease, hospital admission or death because the target population were young.
Despite the results, AstraZeneca said it believes the jab will still protect against severe disease caused by the mutation.
How effective is the Moderna vaccine?
A smaller proportion of people in the UK have been given the Moderna vaccine, which came on stream in April.
Moderna’s vaccine efficacy in preventing Covid illness, including severe cases, is high at 94.5 per cent, according to trial results in November.
Research by US health officials showed the jab is actually about 90 per cent effective at preventing infection two weeks after the second dose.
The US firm have said laboratory tests found the Kent variant had “no significant impact” on the jab’s performance.
Unfortunately it is not yet known if the Moderna jab will give a high level of protection against the Indian variant.
It has not been included in studies by PHE because too few people have received the jab for the agency to study it properly.
Marco Cavaleri, head of vaccines at the European Medicines Agency, said the data appeared “rather reassuring” that vaccines made by Pfizer and Moderna would protect against the variant first seen in India.
South African variant
Moderna is trialling a vaccine produced specifically to target the South African strain.
It said earlier this month the “tweaked” jabs appear to produce antibodies that successfully kill the virus in lab studies, The Guardian reported.
It came after studies suggested that current vaccines would not work as well, with the Moderna jab producing an antibody response six-fold smaller against the South African variant.