Singapore won't get herd immunity even with 100% COVID infection rate: Ong Ye Kung

An estimated six in 10 Singapore residents have likely caught COVID-19, said Health Minister Ong Ye Kung on 1 August, 2022, in Parliament. (SCREENCAP: MCI Singapore/YouTube)
An estimated six in 10 Singapore residents have likely caught COVID-19, said Health Minister Ong Ye Kung on 1 August, 2022, in Parliament. (SCREENCAP: MCI Singapore/YouTube)

SINGAPORE — Even if 100 per cent of Singapore's population is infected with COVID-19 or vaccinated against the novel coronavirus disease, Singapore will not achieve herd immunity, said Health Minister Ong Ye Kung in Parliament on Monday (1 August).

Responding to a question from Marine Parade GRC Member of Parliament (MP) Seah Kian Peng, Ong elaborated, "It's no longer a function of percentage-coverage of vaccinations or infections, but it is the fact that it is a fast-mutating virus and it will escape prior infections’ and vaccine protection."

As such, Singapore should not aim for herd immunity where "we think the virus will disappear", but rather live with it and protect against severe illnesses, he said.

During his speech on the novel coronavirus situation in Singapore, the multi-ministry COVID-19 taskforce co-chair said that Singapore has yet to be conferred herd immunity, even as an estimated six in 10 Singapore residents have likely caught the disease.

The estimation is inferred from the Ministry of Health's (MOH) systematic monitoring of blood samples from routine polyclinic cases and other healthy volunteers for signs of previous infection.

In Singapore, some 1.7 million infections have been reported on record, or about 30 per cent of Singapore's population.

"By and large, scientists around the world do not think herd immunity is achievable because the virus will continue to mutate, escape the protection of vaccines and then infect people," he added.

What is achievable is “population protection" against severe illness through vaccinations, Ong added.

During the Omicron BA.2 wave at the beginning of the year, 2.4 per cent of cases needed hospitalisation, while that figure dipped to 1.9 per cent during the current wave driven by the Omicron BA.5 variant.

The actual percentages are lower because of unreported cases, according to Ong.

Nonetheless, Singapore has hit a "plateau" in its vaccination efforts to encourage a three-dose regimen, he noted, adding that 40,000 people aged 60 and above have not received their booster shots even when they are eligible.

Another 40,000 have not completed two doses, Ong said.

Infection rate falling in Singapore

While Singapore is still in the middle of an Omicron BA.5 wave, infection numbers have been falling over the last 10 days, Ong noted, adding that the wave is likely to subside further this week.

The week-on-week infection rate in Singapore has fallen to below 0.9 over the last week, he added. The rate refers to the ratio of community cases for the past week over the week before, where a figure of more than one means that the number of new weekly cases is increasing.

Based on the "worst case scenario" projection of the current wave, there are plans to set aside up to about 1,000 hospital beds for COVID-19 patients, said Ong, noting that not all of them had to be activated during the wave.

Reinfection rates have been low in Singapore during the current wave, lower than those in many other countries, Ong replied to a parliamentary question by Tanjong Pagar GRC MP Joan Pereira.

This is likely due to Singapore's good vaccination coverage and having gone through a large Omicron BA.2 wave earlier this year, he said.

MOH is watching the reinfection numbers very closely because they will indicate the likely timing of future waves, Ong added.

Findings showed that the chance of getting reinfected with COVID-19 is "very rare" for those who had caught it over the last three months. The probability of getting reinfected is about three per cent that of an uninfected person for those who caught COVID-19 four to seven months ago, Ong said.

Comparatively, the probability of getting reinfected was about 20 per cent that of an uninfected person for those who caught the Delta variant last year.

"Of course, this picture will change as time goes by and the protective effect of prior infections will wane. Hence, having been infected by COVID-19 before should not be a reason to let your guard down,” he said.

MOH to report reinfection numbers daily

Because the number of reinfections will likely increase, such numbers will be included as part of MOH's daily case count from Monday to reflect a "more accurate reflection of the pandemic situation" here.

“In the past, we report the number of patients who have been infected every day, so a patient who has been infected twice, we count him only once...With more reinfections, from today, we will report the infection episodes instead of infected persons,” Ong said.

He also cautioned Singapore to be more alert to new variants that are more infectious and that can lead to more severe illnesses or evades the protection of current vaccines.

"We hope it will not happen. But many countries in the northern hemisphere are worried about that...If we encounter such a variant, I'm afraid social restrictions will become necessary again," stressed Ong.

At least six local cases and two imported cases of the new Omicron BA.2.75 strain, unofficially dubbed “Centaurus”, have been detected in Singapore.

Globally, there are fears that BA.2.75 may quickly overwhelm the current dominant BA.5 and BA.4 strains as it has more unique mutations on the spike gene that have not been observed in other variants.

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