Will booster jab offer better protection against variants?
Although only about 10 percent of Thailand’s adult population has had a COVID-19 jab so far, moves to find “booster” doses are already underway.
Only two brands of vaccine are currently available in Thailand, AstraZeneca and Sinovac, and both require two doses for full inoculation. However, the emergence of several variants of the virus is putting even fully vaccinated people at risk.
Hence, medical experts say it may be time for Thailand to consider providing a booster.
What is a vaccine booster?
A booster is a follow-up dose of vaccine, which re-exposes the recipient to the immunizing antigen in order to strengthen the body’s immunity against the virus.
With the COVID-19 outbreak continuing unabated, a booster dose will help maintain recipients’ immunity not just over time, but also against the different variants and mutations.
Variants on the rise
This week, the Medical Services Department said Thailand had recorded more than 650 cases of the Delta variant first found in India and at least 38 cases of Beta, first found in South Africa. The Alpha variant from the UK remains the prevalent strain in Thailand but health experts warn it could soon be overtaken by the highly infectious Delta.
All three strains are more easily transmissible than original COVID-19 and have been labelled variants of concern by the World Health Organization.
About 2,000 medical science graduates will be mobilized to help in the treatment of COVID-19 patients and over 400 hospital beds will be made available, according to the Centre for COVID-19 Situation Administration (CCSA), as Thailand battles its worst outbreak to date, which has seen 2,000-4,000 new daily infections and dozens of deaths for several consecutive weeks.
Thailand’s COVID-19 situation
Alpha sparked Thailand’s third wave of COVID-19 infections in April, with the number of cases and deaths soaring daily.
As of Thursday (June 24), Thailand’s confirmed cases rose to 232,647 with 1,775 deaths. The third wave accounts for over 90 per cent of cases and deaths.
Third dose for Thais
Leading virologist Dr Yong Poovorawan, from Chulalongkorn University, forecasts that Delta will soon become the dominant strain in Thailand.
Neither Sinovac nor AstraZeneca provide high protection against symptomatic infection from the Delta variant, he adds.
“But if we arrange for the third dose at the right time, immunity levels can rise 10-fold.”
Prof Dr Thiravat Hemachudha, director of Thai Red Cross Emerging Infectious Diseases Health Science Centre, suggests that the booster dose should be of a different brand from the two COVID-19 vaccines currently available here.
Third dose elsewhere
The United Arab Emirates and neighbouring Bahrain are offering Pfizer vaccine in booster shots for those who have taken two shots of Sinopharm.
Bahrain is fighting its biggest wave of cases, while the infection rate in UAE has doubled compared to seven months ago.
Pfizer-BioNTech has become the sixth vaccine to be approved by Thailand’s Food and Drug Administration (TFDA), for emergency use in the country, said TFDA Secretary-General Paisal Dunkhum today (Thursday). Pfizer’s “Comirnaty” vaccine is an mRNA vaccine which encodes a mutated form of the spike protein found on the surface of the SARS-CoV-2 virus, which causes COVID-19, producing an immune response.
Chula’s CU Centre of Excellence in Clinical Virology is conducting a study on combining COVID-19 jabs to determine side effects, efficacy and interchangeability.
Volunteers in the study will get one shot of AstraZeneca and one shot of Sinovac.
Using different vaccine types – known as heterologous prime-boost vaccination – to boost immunity is a longstanding practice in the medical realm.
And it has already been used to combat COVID-19. Several countries, notably South Korea, are mixing and matching coronavirus vaccines.
Some 760,000 South Koreans who have received their first dose of AstraZeneca will be offered the Pfizer vaccine, following delayed delivery of AstraZeneca shots.
The most prominent public figure to have received a combination of COVID-19 vaccines is Germany’s leader Angela Merkel. She received an AstraZeneca shot in April and a Moderna jab earlier this month.
Experts believe mixing COVID vaccines may be a good idea, but research to prove the theory is still ongoing.
By Thai PBS World’s General Desk