60% of Singapore residents have caught COVID-19, but this doesn't mean there is herd immunity: Ong Ye Kung

SINGAPORE: An estimated 60 per cent of Singapore residents have likely caught COVID-19 before, but this does not mean the country now has “herd immunity”, Health Minister Ong Ye Kung said in Parliament on Monday (Aug 1).

On record, there are about 1.7 million reported cases, which is about 30 per cent of the population.

The ministry also systematically monitors blood samples from routine polyclinic cases and other healthy volunteers for signs of previous infection, Mr Ong said.

“From these samples, we estimate about 60 per cent of local residents are likely to have been infected with COVID-19.”

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

What is achievable is “population protection against severe illness” through vaccinations, Mr Ong said.

This is what enables the healthcare system to weather an infection wave, even with high case numbers, because the translation of infections into severe illnesses is low, he said.

The minister was responding to MP Seah Kian Peng (PAP-Marine Parade) who asked for the percentage of the population that has been infected and whether Singapore has attained herd immunity with such an infection level.

While Singapore is still in the middle of an infection wave driven by the Omicron variant BA.5, over the last 10 days, infection numbers have been falling, Mr Ong said. The week-on-week infection ratio has dipped below 0.9 over the last week, and “we should see the wave subsiding further this week”.

During the last Omicron wave at the beginning of this year, 2.4 per cent of infected persons needed hospitalisation. During the current wave, 1.9 per cent have ended up in hospitals, Mr Ong said, adding that the actual percentages are lower because of unreported cases.

COUNTING REINFECTIONS

While Singapore’s reinfection rate during the current wave has been low – lower than many other countries – this is likely to increase as protection of vaccines and prior infections wanes, Mr Ong said.

The way the ministry reports the number of cases will change to reflect this, he said.

“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 them only once, and there are very few of them. With more reinfections, from today, we will report the infection episodes instead,” Mr Ong said.

“This will be a more accurate reflection of the pandemic situation.”

He was responding to MP Joan Pereira (PAP-Tanjong Pagar) who asked about the incidence of reinfections.

He added that his ministry has been watching the reinfection numbers closely because it will inform them of the likely timing of future waves.

“Our observation is that for those who were infected over the last three months, the chance of getting another infection is very rare. For those infected four to seven months ago, the probability of getting infected again is about 3 per cent that of an uninfected person.”

The minister added for someone who was infected with the Delta variant last year, the probability of getting infected again is about 20 per cent that of an uninfected person.

However, these probabilities will change as time goes by and the protective effect of prior infections wanes.

“Having been infected by COVID-19 before should not be a reason to let your guard down totally,” he said.

STRESS ON HEALTHCARE SYSTEM

While MOH is promoting the use of telemedicine for mild COVID-19 cases, people must be realistic that in a big infection wave, the healthcare system will come under stress, the minister said. Waiting times at private clinics, polyclinics and hospitals will "inevitably go up", he added.

"We did not tighten any social restrictions during the current wave ... However life is not as normal in our hospitals. Without additional social restrictions, our healthcare system is bearing the brunt of the current wave," he said.

"Healthcare workers have been very busy. Polyclinics and our general practitioner clinics also saw higher patient volumes."

Mr Ong was responding to Ms Pereira, who asked about coping with the spike in the number of patients at healthcare institutions. 

“In such a situation, the key is to ensure hospitals are not overwhelmed, and that those who need urgent care can be attended to promptly. Fortunately, we are generally able to achieve that,” he said.

He added that the first important measure the Government took is to set aside sufficient bed capacity to cater to COVID-19 patients.

There are plans to set aside up to about 1,000 hospital beds for COVID-19 patients, Mr Ong said. In the course of this infection wave, not all the beds had to be activated, he said.

He was responding to MP Louis Chua (WP-Sengkang) who asked for the bed capacity in private and public hospitals for COVID-19 hospitalisations. 

The Government also eased the workload of hospitals by transferring lower-risk patients to COVID-19 treatment facilities and discharging those staying long term back to community care facilities like nursing homes, Mr Ong said. 

Hospitals also have to manage their own demand for beds and have cut down on "business-as-usual" workload by about 5 per cent, comprising mostly elective surgeries, Mr Ong added.

During the current infection wave, the ministry did not suspend the leave of healthcare workers. Absenteeism in hospitals due to the current COVID-19 wave has been lower this time, at around 2 per cent.

"As far as we can determine, while there had been some transmission within hospitals, overall hospital-acquired COVID-19 infection has been low, and very likely lower than community acquired infections and this is because of good infection control measures in hospitals," he said.

He was responding to Mr Yip Hon Weng (PAP-Yio Chu Kang), who asked if hospital-acquired COVID-19 infections are contributing to a bed crunch. 

Mr Chua also asked for the number of foreign patients who come to Singapore to seek inpatient treatment or day surgery at hospitals in Singapore and for the current utilisation rates of existing bed capacity by foreign patients in hospitals.

That number has “historically been small”, said Senior Minister of State for Health Janil Puthucheary.

Between 2017 and 2019, public and private hospitals saw about 32,000 foreign patients annually, or about 3 per cent of all inpatients and day surgery patients.

These numbers have since fallen by 80 per cent compared to pre-pandemic levels, Dr Puthucheary said.

"In 2021, there were just 6,000 episodes comprising less than 1 per cent of total cases seen in hospitals," he added.

PROTECTIVE EFFECT OF VACCINES

In response to a question from MP Shawn Huang (PAP-Jurong) who asked when the protection from vaccines will start to wane, Mr Ong provided data.

MOH’s empirical data shows that after 10 months, the protective effect of three doses of mRNA vaccines remains strong in preventing severe illness.

That is why as of now, the recommendation is for those who are 80 years old and above to receive a second booster shot, or a fourth vaccine dose, to better protect against severe disease. While the protection for this age group is not waning, it is generally lower than younger age groups, he said.

For those aged 50 to 79, although the protection continues to be strong, this is also the age when chronic illnesses start to set in, so they will be offered the second booster if they want to take it because they are travelling, or worried about their health because of underlying illnesses.

“Our experts are actively studying the benefits of a fourth shot for the 60 to 79-year-olds in further reducing the likelihood of severe illness. We will announce their recommendations shortly, and once ready,” he said.

As for those below 60 years old, they have the protection of both the third shot and age, and currently do not require a second booster if they are healthy, Mr Ong added.

Mr Ong noted that there are about 40,000 seniors aged 60 and above who have not received their booster shots despite being eligible. Another 40,000 seniors have not completed two doses yet, he said.

"All of them are vulnerable to severe illnesses if infected, and we will continue to try to reach out to them through our mobile vaccination teams, our home vaccination teams," he said.