Distinctions between booster and third doses

THE vaccination status of those required to get their Covid-19 booster shot will be deemed “incomplete” if they fail to do so by February next year, and they will not be able to enjoy the benefits given to fully vaccinated people. This was announced by the Health Minister at a press conference on Dec 16.

Although Covid-19 vaccination continues to be effective in preventing recipients from getting a severe form of the disease, recent data indicates that the vaccine becomes less effective over time – particularly in people aged 65 and older – and in preventing infection or milder illness symptoms.

The recent emergence of the Omicron variant (B.1.1.529) emphasises the importance of Covid-19 vaccination and boosters. Recent evidence also suggests that vaccine effectiveness against Covid-19 infection is decreasing over time among healthcare and other frontline workers.

This lower efficacy is most likely due to a combination of decreasing protection with time since vaccination and the Delta and Omicron variants’ higher infectiousness.

The booster programme in Malaysia has now been expanded to include all individuals aged 18 and above as of Nov 25. Priority is given to frontline health, safety and defence personnel, people over the age of 40, people with comorbidities, residents and staff at long-term healthcare facilities, pregnant women and people who need to travel overseas.

Only three vaccines – those manufactured by Pfizer-BioNTech, Sinovac Biotech Ltd and AstraZeneca – are currently approved for use as booster shots and third doses in Malaysia.

It is critical to understand the distinctions between a booster dose and third dose.

A booster dose is an additional dose given on top of the previously administered doses. Sinovac vaccine recipients will be eligible for boosters three months after the date they received their second dose while those fully vaccinated using Pfizer-BioNTech and AstraZeneca vaccines will be able to get theirs six months after their date of completion.

The third dose, on the other hand, is an additional dose given to people with moderately to severely compromised immune systems. This extra dose is meant to improve immunocompromised people’s response to their initial vaccine series. The third dose is given 28 days after the second dose, regardless of the type of first two vaccines received.

Booster doses are also highly recommended for women who are pregnant and breastfeeding. The advantages of taking a booster dose include protecting pregnant moms from severe Covid-19 illness, as evidence about the safety and effectiveness of Covid-19 vaccination during pregnancy and lactation grows. According to these findings, the benefits of receiving a Covid-19 vaccine outweigh any known or potential risks of vaccination during pregnancy and breastfeeding.

So make sure to get your booster when you are eligible to ensure the country does not see another spike in infections.

DR LIM YIN CHENG , PROF DR VICTOR HOE , Occupational and Public Health, Department of Social and Preventive Medicine, Faculty of Medicine, Universiti Malaya