In most countries that have reached a 90 per cent vaccination rate, like Malaysia has for its adult population aged above 18, the number of Covid-19 cases will see a downward trend.
However, there is a return of cases in most instances in a U-shaped curve, said Dr Chow Ting Soo, an infectious disease consultant at Penang Hospital.
"This is because of the emergence of stronger variants and variants that are more highly transmissible.
"Besides, immunity conferred by the vaccine will wane after three to six months, which means that even post-vaccination, breakthrough infections are anticipated and expected.
"This is what we are preparing to face as the re-emergence of cases is expected or the so-called fourth wave," he said.
Dr Chow added that if this were to happen, there is a worry that the healthcare system could collapse and possibly impact the economy, which is why booster shots are necessary.
"For those who are more than 40 years old and those above 18 with comorbidities, there is a need for them to go for booster shots," he said.
Dr Chow, who is also Penang state's infection control coordinator, said these jabs were essential to flatten the curve, slow the infection rate and keep the healthcare system from collapsing.
On Tuesday (Nov 23), Malaysian Deputy Health Minister Aaron Ago Dagang said the government was prepared to face the eventuality of a fourth wave of Covid-19 infections in the country following the Melaka state election last Saturday.
He said the effects could be detected only after 10 to 14 days.
"We are monitoring the situation. The government is aware and is ready to face the possibility of the fourth wave happening in the country," he said in response to a question in the Dewan Rakyat, or Lower House, yesterday.
Virologist Kumitaa Theva Das said that if the country's fourth wave were to kick in, there would be another surge in death and hospitalisation rates.
"In Europe, the spike in cases has primarily occurred among the elderly (who received their vaccine shots much earlier in the year) and among kids who are not eligible for inoculation," she said, adding that the government did not want this to occur in Malaysia.
"The immediate concern is how much longer can the healthcare system cope if there is an increase in Covid-19 cases. When we saw record-high cases in the middle of the year, many hospitals were pushed to the brink, and we don't want to see that happening again.
"According to data on CovidNow, there has been an increase in deaths in Kedah, Melaka, Penang, Negri Sembilan and Terengganu in the past two weeks.
"There has also been an increase in hospitalisation in Johor, Kelantan, Pahang and Penang, and an increase in cases in Kedah, Kelantan and Melaka.
"With cases rising in many states, it is important to remember to practise the SOP (standard operating procedure)," said Dr Kumitaa.
Dr Venugopal Balakrishnan, a lecturer in molecular medicine at Universiti Sains Malaysia's Institute for Research, said that if another Covid-19 wave were to occur, more infections from variants of concern such as the Delta strain and others might occur.
"We will see a rise in the number of cases. This situation may end up in another movement control order (MCO) or targeted MCO.
"When there is an increase in cases, there will be consequences such as hospital beds being fully utilised and an increase in ICU (intensive care unit) usage. The economy will also be affected," he said.
Dr Venugopal added that Malaysia has experienced three Covid-19 waves.
The first wave started when the first case was reported on Jan 25 last year, but the number of cases subsequently went down.
The second wave started with the Sri Petaling cluster, which saw the first MCO being implemented on March 18, 2020.
The MCO brought the number of Covid-19 cases down gradually and on June 10, the recovery MCO was implemented.
The third wave kicked in on Sept 8, 2020, mainly due to the Sabah election and Tembok cluster.- Straits Times