With the new coronavirus strain Omicron lurking around the corner, booster jabs are to be expedited. But as Thailand has administered quite a few mix-and-match vaccination formulae, the public health authorities must quickly clarify what type of vaccine can be safely administered as booster shots for which formula.
With the first fatality linked to Omicron reported in the United Kingdom, the case is strong for the population to get booster doses. Many people, however, are left in the dark as to what type of vaccine should they get on top of what they already had and how far between shots should they wait.
At present, each province or vaccine centre seems to endorse different intervals.
There is a question also whether the recommended intervals are based on scientific studies or just random estimates.
Public Health Minister Anutin Charnvirakul said on Monday that the waiting time for the second Covid-19 vaccine and booster shot will be reduced from four-six months to three months. The reduction is aimed at strengthening people's immunity in preparation for local transmission of the new variant which has spread to more than 60 countries in a few weeks.
A new study by Oxford University recently confirmed that two doses of AstraZeneca or Pfizer -- the two vaccines that have been used predominantly in the UK -- offer little protection against infection by Omicron. The finding was in line with earlier research from the UK Health Security Agency.
Pfizer and BioNTech also provided an update earlier this week that its preliminary laboratory studies demonstrated that three doses of its Covid-19 vaccine could neutralise Omicron while two doses show significantly reduced neutralisation.
The case for booster jabs and their timing might be simpler in the UK where only two types of vaccines have been mainly administered. Here in Thailand, however, several same-type and mix-and-match formulae have been in use. These include people who have received Sinopharm-AstraZeneca, Sinovac-AstraZeneca, AstraZeneca-Pfizer, and many other combinations of the five Covid-19 vaccines authorised for use in the country.
There remain a lot of questions such as which type of vaccine would be best as boosters for these different formulae? Should those who received inactivated virus vaccines like Sinovac as the first and second shots go for the adenovirus kind like AstraZeneca? Or mRNA?
Some doctors have given advice on which type of vaccines should be used following the primary series and at what intervals.
The recommendations seem to be made on a personal basis, however. In the end, they acknowledge the fact that information remains inadequate about Omicron and the efficacy, or risk, of the third or fourth booster shot.
Ironically, some of the doctors and virologists have simply said that it will be up to individuals to weigh the risks or benefits and come up with their own decision.
That should never be the case. If the government believes that Omicron will spread quickly and possibly take over from Delta as the dominant strain causing illnesses, it should speed up studies for the safe administration of booster shots for each and every mix-and-match vaccine formula it has administered.
A clear guideline is urgently needed, together with support studies and associated risk profiles which will increase public confidence in booster shots.