COVID-19 Vaccine Boosters the Way Forward?

Are COVID-19 Vaccine Boosters the Way Forward?
There are growing concerns that COVID-19 vaccines do not offer sufficient protection against new variants of the SARS-CoV-2 virus. Israel has already started to offer booster shots of the Pfizer vaccine to at-risk adults, and the United States is in talks with Pfizer about introducing these shots for the most vulnerable.

There is growing evidence that people who have received COVID-19 vaccines are less likely to become infected with the virus that causes this disease and that if they do, they are less likely to have symptoms of severe illness.

Are COVID-19 Vaccine Boosters the Way Forward?

Are COVID-19 Vaccine Boosters the Way Forward?
However, evidence is also emerging that existing vaccines may offer less protection against new variants of SARS-CoV-2, such as the delta variant.

One study, for example, showed that 95% of people who received both doses of the Pfizer-BioNTech or Oxford-AstraZeneca COVID-19 vaccine had a weaker immune response to the delta variant than to previous strains.

People who received just one dose of either vaccine had a very weak immune response, which suggests that a single dose of one of these vaccines does not offer adequate protection.

The Health Ministry of Israel also released a statement saying that the effectiveness of the Pfizer-BioNTech vaccine in preventing symptomatic COVID-19 fell to just 64% at 6 months post-vaccination. It noted, however, that two doses of Pfizer are still able to prevent serious illness in 93% of cases.

As of yet, the U.S. has made no decision as to whether they will approve access to booster vaccines. However, the Centers for Disease Control and Prevention (CDC) and the Food and Drug Administration (FDA) said in a joint statement that they are “prepared for booster doses if and when the science demonstrates that they are needed.”

What are vaccine boosters?
Vaccine boosters are additional vaccine doses that should provide extra protection against disease, as the effects of some vaccines may wear off over time.

Vaccine boosters are common for many viral infections, including the flu, which requires a booster every year, and tetanus, diphtheria, and pertussis (DTaP), for which a booster is necessary every 10 years.

For some vaccines, receiving smaller doses more often is more effective than getting a single large vaccine dose.

This approach allows the immune system to build its immune response sustainably. When the immune system remembers certain antigens that previously activated it, it can respond much quicker the next time it encounters them.

Although many vaccine boosters are identical to the previous doses, some are modified to enhance their efficacy. The flu vaccine, for example, changes every year to respond more effectively to new mutations of the influenza virus.

Why take booster doses?
There are generally two reasons why people might consider vaccine boosters. The first is that immunity naturally wanes over time. Without repeated exposure to certain antigens, the immune system may become less able to prevent infection or disease. Vaccine boosters help the immune system maintain a protective response.

“Another reason we may need booster vaccinations is viral variants,” a spokesperson from the COVID-19 Vaccine Team at the University of Oxford told Medical News Today. They went on to explain:

“Some variants have evolved to avoid some parts of our immune response, which means they can more easily infect those who have an existing immune response to the virus — i.e., those who have been previously infected or vaccinated. However, the virus cannot avoid all parts of our immune response. A booster vaccination is helpful, as it can improve the parts of our immune response the viral variant cannot avoid.”

“Alternatively, we can use a booster vaccine that specifically targets the viral variant. This works by producing a new immune response to the parts of the virus which have changed from the original vaccine whilst also improving the existing immune response against the unchanged parts of the virus, which also should help protect against other variants,” they added.

Source: Medical News Today

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