As COVID-19 cases rise again, how important is a second booster shot?

The World Health Organisation has said the BA.4 and BA.5 subvariants contributed to a rise of infections in 110 countries, causing overall global cases to increase by 20 per cent.

“The pandemic is changing but it’s not over. We have made progress but it’s not over,” its Director-General Tedros Adhanom Ghebreyesus said in a statement last month.

Malaysia is no exception. Health director-general Tan Sri Dr Noor Hisham Abdullah revealed that hospitalisation rates have increased by 15 per cent in the past week.

This is along with a 67.5% hike in the number of cases referred from COVID-19 Assessment Centres (CAC) to Low Risk COVID-19 Quarantine and Treatment Centres (PKRC).

The country recorded 3,934 infections yesterday, bringing the tally to 4,604,670 cases since the pandemic began. There are currently 36,894 active cases.

The Health Ministry has already warned of a resurgence as five BA.5 cases have been detected in Malaysia.

As of June 30, officials confirmed 13 cumulative cases of Omicron sublineage variants, including six BA.2.12.1 cases and another two BA.5.2 cases.

However, no cases of the BA.4 sub lineage have been recorded so far.

Speaking to Astro Awani, Sunway University President and Immunologist, Professor Sibrandes Poppema, explained that vaccines help boost one’s antibody and T-cell response to the virus.

The antibody response helps prevent infection if effective against a given variant, while the T-cell response is present to moderate the seriousness of the disease.

In general, the efficacy of each COVID-19 vaccine begins to wane after around six months.

Current data, said Poppema, has found that existing COVID-19 vaccines are not as effective for the BA.4 And BA.5 sub-variants as they were for earlier strains of the virus.

This has raised concerns on the need for a fourth dose and whether the antibody response can still prevent infection from the virus.

He noted that there was also the upcoming BA.2.75, which is gaining ground in India and gradually popping up in other countries such as the United States.

There is much more to learn about BA.5 and other contagious strains, but Poppema advised people to consider registering for their fourth dose of the vaccine.

“It is still important to get a booster because it will raise your antibody response a little bit, even against those new variants,” he said.

“More importantly, it will also raise your T-cell response and that is much more independent from the variants. The T-cell response is what makes it much less likely for you to get seriously ill.”

He added that it was especially crucial for those from high-risk groups, namely the elderly and those with comorbidities, to get another jab.

“We’re talking about people with obesity, diabetes, hypertension–those are the people at highest risk.

“When they get infected, they can get very serious diseases and might end up in intensive care and even die. So for them, it’s extremely important to get the second booster shot.”

Up to seven million Malaysians have yet to receive their first booster shot against COVID-19, as of July 11. While the booster dose is not mandatory, Prime Minister Datuk Seri Ismail Sabri Yaakob urged them to register for their third round of inoculation immediately due to the rise of new infections in the country.

It is recommended for everyone to receive their fourth dose of the vaccine, including those who have tested positive for the virus in the past.

“When you’ve had a COVID-19 infection, of course you will have some immunity but that will also wane over time,” said Poppema.

“After six months of having had COVID-19, you should get your next booster shot.”

Despite the relaxed restrictions and the country’s transition into endemicity, Poppema reminded the public to remain vigilant and continue adopting public health measures.