Mixing booster jabs: What’s the best combination of Covid vaccine for your third jab?


Every eligible over-18 in the UK is being urged to get a booster dose of a coronavirus vaccine in order to protect themselves from the rapid spread of the Omicron variant. However the three most common vaccines available in the UK – AstraZeneca, Pfizer and Moderna – offer different levels of protection against symptomatic infections. Here’s everything we know so far about the different vaccines.

After Boris Johnson’s pledge to get every eligible adult in the UK a booster jab by the end of December, millions of Britons braced cold weather to go out and get their third jab last week.

Studies of vaccine effectiveness against Omicron are still in their infancy, as the variant was discovered so recently.

However, the earliest analysis is clear while there may be some variety in effectiveness between the vaccines, the most important thing is to get a booster jab.

Mary Ramsay, Head of Immunisation at the UK Health Security Agency (UKHSA), said: “These early estimates should be treated with caution but they indicate that a few months after the second jab, there is a greater risk of catching the Omicron variant compared to Delta strain.

“The data suggests this risk is significantly reduced following a booster vaccine, so I urge everyone to take up their booster when eligible.”

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While Pfizer, Moderna and AstraZeneca vaccines all reduce the risk of severe disease and hospitalisation, the data below focuses on their effectiveness against symptomatic infections.

If you have had two doses of Pfizer

If you received two doses of the Pfizer vaccine earlier this year, or last year, your protection against a symptomatic infection from the Omicron variant is estimated to be around 40 percent.

By following up two doses of Pfizer with a booster dose of the same vaccine, your protection against the symptoms of Omicron is thought to increase to 75 percent, according to early analysis by the UKHSA.

Based on the data we have so far, which could change once we have concrete numbers on the Moderna booster vaccine, a triple dose of Pfizer offers the strongest protection against a symptomatic infection of Omicron.

However, Moderna and Pfizer are offered with “equal preference” as they are likely to offer a similar level of protection against coronavirus variants.

A statement from the Joint Committee on Vaccination and Immunisation said: “Both the Moderna (50 microgram) and Pfizer-BioNTech (30 microgram) vaccines have been shown to substantially increase antibody levels when offered as a booster dose and should be used with equal preference in the COVID-19 booster programme.”

Against the Delta variant of coronavirus, those who are triple-jabbed with Pfizer can expect 94 percent protection against a symptomatic illness, UKHSA says based on data from the over-50s.

If you have had two doses of Moderna

According to a study published in the British Medical Journal, two doses of Moderna were found to offer 86.7 percent protection against infection from the Delta variant of coronavirus.

Data is not yet available from Moderna on the effectiveness of their vaccine against the Omicron strain of coronavirus, as it has not yet been peer-reviewed.

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However, the company has said laboratory testing suggests a booster dose of their vaccine is effective against Omicron.

According to Moderna, a 50mg dose of Moderna, which is the amount offered across the UK, is reported to give a 37-fold increase in antibodies.

Moderna is developing a vaccine specific to the Omicron variant, but this will take some time to reach our arms as it will have to go through rigorous testing first.

If you have had two doses of Astrazeneca

If you were in the priority groups to be called up for a vaccine, it’s likely you were given two doses of the Oxford AstraZeneca vaccine.

Early analysis has suggested AstraZeneca is not particularly effective against the Omicron variant.

AstraZeneca is not being offered as a booster jab because it is thought mRNA vaccines, such as Pfizer and Moderna, give a stronger boost to your vaccine protection.

However, if you follow your two doses of AstraZeneca with a booster shot of Pfizer, you can expect around 70 percent vaccine effectiveness against Omicron symptoms, the UKHSA says.

That’s just five percent below the effectiveness of a triple dose of Pfizer, and a lot more effective than two doses of AstraZeneca alone.

If you had two doses of AstraZeneca, then received a shot of Pfizer as a booster jab, it should be 93 percent effective against the Delta variant, according to UKHSA data based on people aged over 50.

Published at Mon, 20 Dec 2021 16:51:00 +0000

Mixing booster jabs: What’s the best combination of Covid vaccine for your third jab?