THE minister and director-general of our Health Ministry are warning us of a new wave of Covid-19 infection if the situation gets worse.

Clinicians treating Covid-19 patients have also highlighted the rise in admissions and intensive care unit (ICU) usage. Are they being overly worried and pessimistic of the country’s Covid-19 situation? Why is this happening when vaccination rates have almost reached 80% for the whole nation?

According to statistics, the R naught (represents the number of people an infected person transmits the disease to) for Covid-19 was 0.87 on Oct 22, and was fluctuating below 1.0 until Nov 11. The R naught has since increased and is fluctuating between 1.0 and 1.05, with the latest at 1.0 on Nov 22. We need to have an R naught of less than 1.0 if we want the total number of infections to reduce.

The lowest number of daily cases of 4,343 was achieved on Nov 7, but there has been no improvement. Instead, the total daily cases increased to 6,380 on Nov 18, and has been fluctuating between 4,000 and 6,000 plus daily.

Concurrently, ICU usage in some states i.e. Selangor, Kuala Lumpur, Kelantan, Penang and Putrajaya has been more than 75%.

Despite 76.6% of the total population being fully vaccinated as of Nov 23, the Covid situation has not improved. The reason behind this is firstly, with the opening of most sectors, with interstate travel allowed, the mobility of people has increased.

If there is poor compliance of standard operating procedures (SOP) among some people, this will lead to transmission among those unvaccinated, as well as vaccinated people.

We should also be aware that vaccination is not 100% effective in preventing transmission, but it is effective in preventing severe Covid illness, hospitalisation and death.

The situation may become more serious with evidence now showing that vaccine effectiveness can wane over time. From the latest data from RECoVaM (Real World Evaluation of Covid-19 Vaccines under the Malaysia National Covid-19 Immunisation Programme), the effectiveness of a vaccine reduces to 68% for Pfizer and 28% for Sinovac in three to five months after full vaccination.

The prevention of ICU admission among individuals vaccinated with Pfizer and Sinovac vaccines after three to five months is 79% and 28% respectively, while the prevention of death for both vaccines was 91% and 76%, respectively. These evidence shows that vaccine effectiveness wanes over time, with the effect from Sinovac vaccine being below 50%, which is a cut off value that is acceptable for vaccine effectiveness.

Concurrently, the analysis on deaths among patients who have taken different vaccines showed that there were 6.0 deaths per one million population for AstraZeneca vaccine, 9.8 deaths per one million population for Pfizer vaccine and 34 deaths per one million population for Sinovac vaccine.

The data showed the waning effect of vaccines, especially Sinovac that wanes faster, caused higher deaths compared to other vaccines. Of course, the findings may be influenced by the patients’ age, who were mostly senior citizens.

This is why the Health Ministry is aggressively pushing for a booster jab among senior citizens and high-risk groups with comorbidities who took the Sinovac vaccine. However, the response for the booster dose has been poor due to the reason that only the Pfizer vaccine has been offered as a booster dose currently.

There are also worries on the adverse side-effects of taking a booster dose that is different from the first two doses. However, mix and match vaccinations, especially for the booster shot has been practised in many countries. For example, Indonesia, Singapore and Chile mixed Sinovac with Pfizer; while Thailand and Cambodia mixed Sinovac with AstraZeneca. The Western countries have also been mixing available vaccines like Pfizer, AstraZeneca and Moderna. There have been no known severe side-effects reported from these countries.

The main reason for mixing Sinovac with other vaccines like Pfizer or AstraZeneca is because they are 94% to 95% effective, while using Sinovac as a booster will only provide 75% vaccine effectiveness.

It is unfortunate that there is a lot of unverified information against mixing Sinovac with Pfizer circulated on social media. We are aware that this has influenced many individuals, who have declined the Pfizer vaccine as a booster dose.

This has jeopardised the efforts by the Health Ministry to provide additional protection to these groups. Our country cannot afford to have another lockdown when our healthcare system is overburdened with more severe Covid infections that require ICU treatment.

We should take note of the new waves happening in some European countries (i.e. Austria, the Netherlands, Germany) that have to re-enforce a lockdown (Austria and the Netherlands) or are contemplating a lockdown (Germany). The people are blaming the governments for not taking early preventive measures to prevent the spike in Covid-19 infections.

Malaysians should value the freedom we currently enjoy, and comply with the SOP at work or during leisure. We should also go for the booster shot to strengthen our immune system. Do not wait for vaccine brands that are unavailable, take the first one that is offered, to protect yourself and your loved ones.

We hope the Health Ministry can expedite the inclusion of Sinovac vaccine in the national immunisation programme. We as Malaysians should do our part so the Covid situation is kept under control, so we can move forward in improving the economic situation.

Prof Dr Moy Foong Ming, Prof of Epidemiology, Department of Social and Preventive Medicine, Faculty of Medicine, University of Malaya. Comments: