Future Doses Will Depend On How Fast Protection Wanes & Mutations
On Wednesday (5 Jan), Singaporeans were told that our vaccination status had an expiry date.
We’d thus need a booster shot of a Covid-19 vaccine to maintain a “fully vaccinated” status.
That might have led to some to wonder whether their vaccinated status would expire again even after the booster, and require a 4th dose, and so on.
Health Minister Ong Ye Kung has responded to this query by saying that it’s “too early to tell”.
Minister Ong clarifies vax queries
Following up from the Multi-Ministry Task Force (MMTF) press conference on 5 Jan, Minister Ong made some clarifications over Facebook on Friday (7 Jan) night.
One of the issues he addressed was something that may have been on Singaporeans’ minds since the booster doses were introduced:
Now that we must get a third dose to get our vaccination status extended, does that mean there will be a fourth, fifth, sixth dose?
After all, if our “fully vaccinated” status can expire in 9 months after 2 doses of mRNA vaccines or 3 doses of Sinovac/Sinopharm, it stands to reason that our status may still expire after a booster dose.
Too early to answer the question
Minister Ong responded that it’s too early to answer that question.
Whether we will need future Covid-19 vaccine doses depends on 2 things, he said:
- how fast the protection from 3 doses wanes
- whether the virus keeps mutating
Thus, if the protection from 3 doses wanes quickly while the pandemic still continues, it’s not too far-fetched to think that another booster might be needed.
Also, if another variant turns up that’s more transmissible and/or causes more severe symptoms, more protection may be needed.
Annual flu vaccine
Minister Ong also compared the situation to that of flu (influenza) vaccines.
Though flu is considered a endemic disease, people take vaccines annually to protect themselves, he said.
That’s because the flu virus keeps mutating, so a new dose is necessary every year.
He also noted that,
Israel is the only country so far to administer a fourth dose for people who are not immunocompromised.
Covid-19 infection equivalent to 1 dose in most cases
Minister Ong also answered questions regarding those who’ve already been infected and recovered from Covid-19.
He compared a Covid-19 infection to “a fairly powerful vaccination shot”.
That’s because if a patient has recovered well without complications, their immune system “would have gone through a strong stimulus”.
Infection plus 2 doses considered boosted
Thus, those previously infected will actually be considered boosted if they’ve also received 2 doses of mRNA vaccine before or after the infection, i.e. V + V + I or I + V + V.
However, people who were infected in between dose 1 and 2 won’t be considered boosted.
This is because the gap of 3-4 weeks between doses is too close, and infection won’t be considered a “separate stimulus”.
Minister Ong reassured, though that there’s “no rush” to get a booster for those previously infected, as the immunity takes longer to wane (i.e. beyond 9 months) in these situations.
They will still be eligible for Vaccination-Differentiated Measures (VDS) till experts say they should boost.
Nevertheless, vaccination centres will still allow them to get the booster if they want extra protection, he added.
No surprise
Singaporeans have been repeatedly told that vaccination and boosters are a key pillar of Singapore Covid-19 strategy.
Thus, it’s no surprise to get confirmation that our vaccination status would have an expiration date.
It shouldn’t be any surprise either that a 4th dose and more will be needed at some point too, as long as the pandemic continues.
Let’s hope that the end of the Covid-19 tunnel will come sooner rather than later.
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Featured image adapted from Lawrence Wong on Facebook.
