Which COVID Booster Is Best? Here’s the (Very Slight) Differences Between Them

which booster

If you’ve had your second dose of the vaccine four or more months ago, it’s now time for you to roll those sleeves up once again and get your booster jab.

There’s good reason for doing so, of course. Mainly, if you’re not immunocompromised and don’t need a third (or even fourth) as part of the normal course of treatment, the booster tops up your immunity which may have waned since your last dose.

Keeping your immunity high is particularly important right now as Australia struggles with the latest wave of COVID, which is sending case numbers soaring to record highs.

Getting your booster is going to offer you good protection against serious illness and reduce the risk of transmission to others.

Currently, Australian healthcare providers offer three different vaccines which can be booked for a booster, regardless of which vaccine you’ve had before. While they all offer similar levels of protection against COVID and its newer strains, there are subtle differences between them.

So, which vaccine should you get as a booster and does it really matter? Here we break down the differences so you can decide which one is right for you.

AstraZeneca Booster

It’s likely that you won’t choose AstraZeneca for your booster dose. Although the vaccine is well tolerated, it’s not recommended by the Department of Health for a booster dose as it hasn’t yet been approved by the Therapeutic Goods Administration for use in this way.

This may be to do with the fact that both Pfizer and Moderna use mRNA technologies in their vaccines while AsztraZeneca uses an adenovirus vector. Adenovirus vectors use a modified version of a virus different to the one being targeted to trigger the immune system into producing an antibody response. This is thought to be less effective than the mRNA approach.

You still can get AstraZeneca as a booster jab, however, if you had a bad reaction to either Pfizer or Moderna or you had AstraZeneca as your primary two doses and want to continue using the same.

Pfizer Booster

The Pfizer booster jab is recommended for those aged five and upwards, meaning it has the broadest application of any booster. It is an mRNA vaccine, like Moderna, which is a newer form of vaccine with a long history. First discovered in the 1960s, the use of mRNA technology has never really had a need until now.

Whether you’ve had other vaccines or not as your primary doses doesn’t really matter as it’s safe to mix and match. In fact, there is good evidence that having a Pfizer booster after a primary course of AstraZeneca may actually offer better protection than three of the same vaccine.

Data released by Pfizer has shown that its booster increases protection against the virus by 25 times compared with just two doses. They also say that tests performed a month after the booster show that people have similar levels of antibodies used to fight COVID, including Omicron, that are equal to those seen to be effective in battling earlier strains.

Some possible side effects of the Pfizer shot appear to be the swelling of lymph nodes after the booster, something that doesn’t appear to be less of an issue with Moderna. Although this might be uncomfortable, it’s not a reason not to get it.

Moderna Booster

Moderna is incredibly similar to Pfizer. It has the same method of action and offers very similar rates of protection. The differences between these two are virtually non-existent, however, there appears to be some data showing that Moderna is slightly less effective in its primary dose against Omicron.

The Moderna booster, however, sparks antibody levels 37 times higher than the primary doses. This is a much greater level than Pfizer’s, suggesting there may be some reason to choose Moderna over Pfizer.

However, this is not a substantial claim, and most studies continue to recommend either one of the mRNA vaccines.

Moderna is, unlike Pfizer, delivered in a half shot of its original dose as the company found that this was sufficient to offer adequate protection over a full dose. This may also minimise the risk of side effects, however, this is not guaranteed.

It Doesn’t Really Matter

In the end, it’s not really that important which vaccine you choose. The important thing is to just get boosted and the best vaccine is likely to be the one which is available soonest.

University of South Florida Professor Michael Teng has said that “there’s such little difference between the Moderna booster and the Pfizer booster that it’s not really worth shopping around at all.”

However, recent studies have shown that mRNA vaccines have been shown to offer a “significant increase” in protection against Omicron than adenovirus vaccines, so if you’ve had AstraZeneca for your primary course, it’s a good idea to get either Pfizer or Moderna.

If you had any bad reactions to either of the mRNA vaccines before, as long as they weren’t too severe, you might consider swapping to a different one. It’s not unlikely though that you could also have a similar reaction to the booster.

So, choose your weapon, whichever one takes your fancy, and gear up for the next stage in the fight against COVID.

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