Vaccines keeping severe cases in check: Experts

The recent surge in Covid-19 cases may take a long time to peak and it is not yet time to ease restrictions here, say experts.

But there is a silver lining, as it appears that vaccines are keeping severe cases from rising as quickly as overall case numbers.

Yesterday marked one month since the current wave of transmission began on Aug 23. From Aug 23 to yesterday, there were 16,226 new local cases of Covid-19 here.

But while the total number of new infections yesterday - 1,504 - was about 15 times that of the 98 cases on Aug 23, the number of those requiring oxygen supplementation multiplied at a lower rate - about nine times - and the number of those in the intensive care unit (ICU) multiplied about thrice.

Professor Dale Fisher, senior consultant at National University Hospital's (NUH) Division of Infectious Diseases, attributed this to the vaccines.

"They are most effective in preventing severe disease and death. So we expect this number to be low, though not zero, in the vaccinated population," he said.

Associate Professor Hsu Li Yang, vice-dean of global health and infectious diseases programme leader at the Saw Swee Hock School of Public Health, agreed but cautioned that there is a lag of about a week between the onset of Covid-19 and deterioration, so there is likely to be a rise in ICU cases in the coming weeks.

Prof Josip Car, director of the Centre for Population Health Sciences at Nanyang Technological University's Lee Kong Chian School of Medicine, said the numbers should be interpreted with caution, as data such as the extent of the actual spread of Covid-19 in the community is still lacking.

Adding that more time is needed, he said: "For now, if we look at the numbers, it is not realistic to interpret them as being completely independent of each other."

Prof Fisher, who is also a professor of medicine at the NUS Yong Loo Lin School of Medicine, said measures should not be eased until the growth in the number of those requiring hospital care falls, which could take "months".

Health Minister Ong Ye Kung had previously said that it typically takes about 30 to 40 days for a transmission wave to peak before falling and stabilising.

Asked about this, Professor Paul Tambyah, a senior consultant at NUH's Division of Infectious Diseases, said no transmission wave lasts forever.

But he also noted that different countries have seen waves of infection with varying durations, for reasons that are not clear.

Prof Hsu explained that waves of infection typically subside when there are fewer and fewer people that the virus can infect, making it harder for the virus to maintain a rapid rate of spread.

"This does not mean that the entire population of the country has to be infected first - there will still be a base level of infection after the wave subsides, just like in the case of influenza," he said.

But by this point, he added, most of the population will have either been infected by the virus or are able to consistently maintain a high level of protective antibodies post-vaccination.

Prof Fisher said it is necessary to allow Covid-19 to become endemic, but this will mean a lot of transmission for some months.

However, the majority of those who are vaccinated will have only mild infections, he said.

Prof Tambyah, who is also a professor of medicine at the NUS Yong Loo Lin School of Medicine, added that there is no need to tighten measures further at the moment.

"We already have very tight restrictions compared with most high-income countries and we are still seeing a surge in cases. It is not clear that further tightening will have any benefits," he said.

The experts all agreed that getting people vaccinated and observing safe management measures are still important despite the large number of cases.

Prof Car said: "The virus can only work on individuals, so we should never let ourselves be cynical at the collective impact of our own individual actions and should always be socially responsible."