By Sola Ogundipe

AS the number of COVID-19  cases continues to rise amidst the spread of the Omicron variant, health officials are encouraging  Nigerians that are eligible to get vaccinated.

As of January 4, 2022, a total of 14.84 million persons or 4.9 per cent of the Nigerian population had received at least one dose of COVID-19 vaccine including boosters, according to Our World In Data.

For those that have already received their first and second jabs, the National Primary Healthcare Development Agency, NPHCDA is urging them to go for their booster shot if it has been at least six months since they received their second jab.

But the protective effect of the vaccines wanes over time, and particularly with the emergence of the highly transmissible Omicron variant, it is recommended that everyone who’s eligible get a booster.

Getting a booster decreases the likelihood of getting infected with the COVID-19 virus or becoming severely ill in the event of contracting the virus.

A “booster shot” is not unique to COVID-19. Booster shots are common for many recommended vaccines.

Giving COVID-19 booster shots can help maintain a higher level of immunity and protection against breakthrough COVID-19 infections. A breakthrough infection occurs when someone who is fully vaccinated gets COVID-19. That person can still get sick—although most vaccinated people will have milder symptoms—and they can spread COVID-19 to others.

While getting a booster is important in stopping the spread of COVID-19,  it takes some time after getting the booster shot before a person becomes fully boosted.

The Director-General of the National Agency for Food & Drug Administration and Control, NAFDAC, Prof. Moji Adeyeye had admonished  Nigerians that have been fully vaccinated to make themselves available for a booster dose.

“I must clarify that booster dose is not going to prevent people from contracting COVID-19 but will prevent people from being hospitalised,” she noted.

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A study by the UK Health Security Agency found that two weeks after a booster dose, protection levels increased to 93.1 per cent for those who had AstraZeneca for their first two doses, and 94 per cent for those who had Pfizer.

A study in Israel found that protection starts to appear about seven days after the booster shot, and then continues to increase for another week.

In the views of Dr Pablo Penaloza-MacMaster, Assistant Professor of Microbiology-immunology at Chicago’s Northwestern University Feinberg School of Medicine, “When you get any vaccine, your immune system mounts an antibody response to fight off future infection.

“Say you got your last COVID-19 vaccine several months ago. As time goes on, your immune response weakens, and a booster shot re-introduces your immune system to the pathogen so it makes more antibody-producing cells.”

He says that a key factor in the process is a type of white blood cell called memory B cells, which remain in the body “waiting” to recognise and fight off the same pathogen.

“Once you incorporate another jab, your memory B cells can sense the proteins made by the virus; then they start making more antibodies. By the time of your booster shot, your memory B cells have already encountered the viral proteins—either once or twice depending on which vaccine series you initially received. The cells can create more and better antibodies against COVID-19—which means you’ll be more protected if you’re exposed to the virus.

Infectious disease expert Dr Amesh A. Adalja, of the Johns Hopkins Centre for Health Security, agrees that most people will experience some positive effects from the booster within a week, but the full effect is believed to kick in two weeks after the booster.

“In general, that’s how the immune system responds and how long it takes to arrive at a peak level of protection.”

Scientific findings suggest that positive effects of the booster shot may start as soon as seven days after getting boosted.

In a trial, people who received Pfizer boosters had a much lower incidence of experiencing symptomatic COVID-19 infections between a week to two months after getting a booster compared to people with just two shots who had received a placebo booster.

Vanguard News Nigeria