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SINGAPORE: While the arrival of a COVID-19 vaccine in Singapore is good news, it will likely take months for life to return to normal as the country develops herd immunity and the effects of the vaccine are further studied, the experts said.
Those who are “lucky” to be among the first to be vaccinated may be hoping to quickly return to a normal way of life, said the vice dean for research at the National University of Singapore (NUS) associate professor Alex Cook.
“But I suspect they won’t be able to avoid wearing a mask and socializing in more than the allowed group size, and so on until enough (people) have been vaccinated for us to be at or close to herd immunity.”
The first shipment of the vaccine developed by the US pharmaceutical giant Pfizer and the German company BioNTech arrived in Singapore on Monday (December 21). This was after Prime Minister Lee Hsien Loong announced last week that the Health Sciences Authority (HSA) had approved the vaccine for use here.
Other vaccines are also expected to arrive in Singapore in the coming months, and the country “will have enough vaccines for everyone” by the third quarter of 2021 if all goes to plan, Lee said.
READ: Singapore-approved Pfizer-BioNTech COVID-19 vaccine, first shipment expected by end of December
Singapore is likely to be among the last Southeast Asian countries to return to normal, but this will likely be months after the last COVID-19 cases in the world, said the president of the Asia Society for Clinical Microbiology and Infection. Pacific, Dr. Paul. Tambyah.
“Yes, and it is a great yes, the vaccine is successfully implemented worldwide and if it works, there is a good chance that the incidence of the disease will drop dramatically around the world and then the WHO (World Health Organization ) can We declare the end of the pandemic and little by little we can return to normality, “he added.
There will be no “major changes” to restrictions here for months, but as more people get vaccinated throughout 2021, Singapore will move closer to herd immunity, allowing preventive measures to be eased, said Professor Dale Fisher. , NUH Senior Consultant and WHO President. Worldwide network for alert and response to epidemic outbreaks.
And even though a vaccine has arrived in Singapore, people need to be punctured to be protected, Associate Professor Cook said.
“So until enough people are vaccinated, society as a whole will not be protected.”
READ: Data on Pfizer-BioNTech COVID-19 Vaccine ‘Rigorously and Thoroughly Reviewed,’ HSA Says
ESTABLISHING THE IMMUNITY OF THE HERD
When there is a critical mass of people who have been vaccinated, measures such as the use of masks, social distancing and border closures can be repealed, as they are no longer necessary to provide social protection from mass vaccination, he added.
The goal of mass vaccination is to achieve herd immunity to protect people and ensure that there are insufficient numbers of people vulnerable to infection to sustain an outbreak, said the dean of the NUS School of Public Health Saw Swee Hock, Teo Yik Ying.
“If there are enough people who have been vaccinated, even if someone is infected, the vast majority of people with whom this infected person interacts will already be vaccinated and will not be infected. That is why mass vaccination with an effective and safe vaccine continues being a very powerful public health measure to protect against an infectious disease, “he added.
Professor Cook said: “In the early stages, those who are vaccinated will be protected and those who have not yet received it will not receive protection. Later, once enough people have been vaccinated, those who are vaccinated will have direct protection and the that they will receive indirect protection, because they will be protected by other people in the vaccinated population ”, he added.
But all this depends on the effectiveness of the vaccine. For example, the situation described assumes that the vaccine protects against infection, and not just disease, said Professor Cook.
VACCINES ARE STILL STUDYING
The experts the CNA spoke with highlighted that all COVID-19 vaccines are still under study, and there are many things that have yet to be established.
For example, experts have yet to identify the immune marker used to measure sufficient protection against COVID-19, said Dr. Leong Hoe Nam, an infectious disease expert.
“We are not sure whether the immunity conferred by the vaccine is long-lasting and permanent,” he said, noting that it is also unclear whether repeat doses will be needed.
For the Pfizer-BioNTech vaccine, two doses are required, to be administered 21 days apart in people 16 years of age and older, according to the vaccination regimen presented by the two companies.
While there is evidence that the vaccine is capable of preventing the disease, evidence on whether the vaccine has protection against transmission from the person being vaccinated to another person is also being studied, experts said.
This means that people receiving the vaccine are unlikely to experience symptoms of COVID-19 infection, including serious complications, Professor Teo said.
“Like some of the responsible governments around the world, Singapore will monitor post-vaccination and in doing so we will be able to modify our public health management measures accordingly, based on the degree of protection the vaccine offers.” added.
READ: First data shows that two doses of Oxford-AstraZeneca’s COVID-19 vaccine elicited a good immune response
The worst case scenario is that the vaccines only prevent disease caused by COVID-19, but not infection, said Professor Cook.
“In that case, if transmission still occurs, then we will not achieve herd immunity through vaccination and protection will not be provided to those who are not yet vaccinated,” he added.
“That would mean that instead of a target vaccination coverage of 90 percent, we would need everyone who can get vaccinated to do so. Actually, it’s not that bad of a result, as our goal is for the majority of people to get vaccinated. get vaccinated anyway. ”
It is not clear whether vaccines prevent the transmission of asymptomatic cases, because the data so far is from people who developed symptoms of COVID-19, said Professor Fisher.
“There are still things we don’t know. How well will it work in the elderly and the immunosuppressed? How long will the effect last or will it wear off and require a boost?” added.
READ: COVID-19: Social gatherings of up to 8 people allowed starting December 28, additional reopening of activities in Phase 3
WHAT IS THE CRITICAL MASS THAT NEEDS TO BE VACCINATED?
Critical mass, or the number of people who need to be vaccinated to prevent further spread of COVID-19 in the community, also depends on the effectiveness of the vaccine, experts told the CNA.
While around two-thirds of the population is usually cited, Dr. Leong said he has “higher expectations” because the coronavirus is easily transmissible and presents asymptomatically.
A 75 percent vaccination rate could possibly block the transmission of COVID-19 in the community, he added.
Professor Fisher noted that 70 percent is a “commonly used number.” This means that if the vaccine is 90 percent effective, 80 percent of Singaporeans will need to be vaccinated, he said, adding that even more than 80 percent would be safer as COVID-19 is “very contagious.”
The number may be even lower than predicted, as not much is known about cross-protection from other related viruses, Dr. Tambyah said.
“For example, the low incidence in Africa despite a lot of surveillance suggests that there may be some immune factors that we do not understand, similarly to the low incidence of illness in children as opposed to influenza or other respiratory viruses,” he added.
The ideal vaccine coverage depends on the number of virus reproduction in the absence of control in Singapore, said Professor Cook.
“We really don’t know what this is, because throughout the pandemic we have been controlling the spread,” he added.
If one person develops a COVID-19 infection and passes it on to two others, this refers to a reproduction number of 2.
With a breeding number of 2, 50 percent of the population should be protected, which means that 55 to 60 percent should be vaccinated based on the vaccine efficacy from trials, said Professor Cook.
If the breeding number is 3, then 66 percent of the population should be protected, so 75 to 80 percent should be vaccinated.
“Given the need to be conservative, I imagine the Health Ministry is aiming higher, maybe as high as 90 percent, but I think some of the impacts of herd immunity will start to be felt with lower coverage,” he added.
Although a critical mass is important for the vaccine to have any effect in preventing the spread of COVID-19 in Singapore, the experts the CNA spoke with agreed that making the vaccine voluntary was the right decision. .
“I think if the vaccine works, people will line up to get it and there is currently no good reason to make it mandatory. It should be encouraged in certain populations like those who care for the elderly, but for the rest, persuasion will be more effective and help build trust, “said Professor Tambyah.
Adding that the decision to make the vaccine voluntary was “responsible and respectful”, Professor Teo said: “A responsible government will want to make sure it offers every opportunity to protect its people.
“This is precisely why Singapore has procured a sufficient supply of vaccines to inoculate all citizens and long-term pass holders in Singapore. However, there will be some people in the population who may not want to accept the offer of a free vaccine, and there can be many reasons why this can happen. ”
Rather than making the vaccine mandatory, it is important that the “vast majority” take it, said Professor Fisher.
“It is much better to allow people to do this voluntarily and it is our role to get people to understand the science and have all their questions answered. Some will tackle it early and certainly some will need some time to understand and feel comfortable.” . added.
“The fact is, the important questions are now answered. Vaccine side effects occur in the post-vaccination period, so we now know enough to be confident. Also, we know that it works, at least in the short term. There really is no reason not to take the vaccine with our current knowledge. “
