What Happens When Second Dose of COVID-19 Vaccines Delays – Here’s What Experts Say

As countries across Africa the world gear up for the second dose of COVID-19 vaccines, it should be emphasised that all the various COVID-19 vaccines have different time interval between when the first and second doses should be taken.

In Ghana, the Health Service last week announced that its initial vaccination policy of having the second dose of the AstraZeneca COVID-19 vaccine administered within an eight-week window period has been extended to 12-weeks.

The latest decision by the Ghana Health Service implies that persons who took the first dose of the vaccine when it was rolled out on March 2, 2021, and were supposed to take the second dose sometime in April will now be in May

The announcement has got some Ghanaians who took the first dose partly worried about how far the first dose can protect them against the virus. As a result, Fact-Check Ghana has put together answers experts have given to questions related to the second dose of COVID-19 vaccines.

Do I have to take the AstraZeneca jab as my second dose or a different one?

As it stands, if you have the AstraZeneca vaccine as your first dose, you need to have the second dose from the same manufacturer (except in rare instances, which will be explained later in this report). The second dose should be issued between four and 12 weeks after the first.

According to the Australian Government Department of Health both Pfizer and AstraZeneca require two doses to provide the best immunity. It is important you get the same type of COVID-19 vaccine. This is because the evidence from clinical trials shows this is effective and is what is approved for use by the Therapeutic Goods Administration.

But why is this important?

When the immune system first encounters a vaccine, it activates two important types of white blood cells.

First up are the plasma B cells, which primarily focus on making antibodies against the pathogen (or germ that causes disease).

Unfortunately, this cell type is short-lived. Your body might be swimming in antibodies within just a few weeks. But without the second shot, there is usually a rapid decline in antibodies against the pathogen.

Then there are the T cells, each of which identifies a particular pathogen to kill it.

Some of these memory T cells linger in the body for decades until they meet their target. This means immunity from vaccines or infections can sometimes last a lifetime. But you usually won’t have many of this cell type until there is a second exposure to that pathogen, which happens through the booster dose.

Do I need a second dose if I’ve already had the coronavirus?

If you’ve had coronavirus, you have probably developed some natural immunity. But experts say there’s not much information about how long that immunity lasts. Having two doses of the vaccine is the best way to make sure you have long-lasting and effective protection against the virus, the British Health Foundation says.

Are there any circumstances when you shouldn’t take the second dose?

An article published on HuffPost indicates that there are some instances where you wouldn’t be advised to have the second dose of the AstraZeneca vaccine, even if you had it as your first. In these cases, you would be offered an alternative by Moderna or Pfizer.

People shouldn’t have the second dose if they have hypersensitivity to the active substance in the jab – COVID-19 vaccine (ChAdOx1-S recombinant) viral particles – or to any of the following ingredients: L-histidine, L-histidine hydrochloride monohydrate, magnesium chloride hexahydrate, polysorbate 80, ethanol, sucrose, sodium chloride, disodium edetate dihydrate.

Of course, you might not know if you’re allergic to any of these ingredients if you haven’t used them already. Here, the best advice is that if you have had a systemic allergic reaction (including anaphylaxis) to a previous dose or any component of the AstraZeneca vaccine, you shouldn’t receive the second lot. If you haven’t, you’re fine to go ahead with your second dose as normal.

A response from the British Health Foundation to the question above advanced that, everyone should get a second dose. However, in a small number of cases, there might be a reason to delay having a second dose. This might be because:

Very rarely, someone might have had a serious reaction to their first dose of the vaccine. This is very unusual – the vast majority of people don’t have anything more than minor side effects. This is extremely rare, but if this does apply to you, speak to a healthcare professional about whether your second dose should be a different vaccine.

This report is produced under the project: COVID-19 Response in Africa: Together for Reliable Information being implemented with funding support from the European Union

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