Although all Covid-19 vaccines approved in Malaysia are highly effective in preventing deaths caused by the disease, they do not completely eliminate such an outcome.
Data released by the Health Ministry yesterday showed a number of Covid-19 deaths among those fully vaccinated were of those inoculated with the Sinovac vaccine.
Overall, fully vaccinated individuals account for 922 (4.9 percent) of the 18,802 deaths recorded in the dataset.
This is despite fully vaccinated individuals making up an increasingly large proportion of Malaysia's population.
These deaths of the fully vaccinated, that occurred between June 7 and Sept 6, were mainly senior citizens (744; 80.6 percent), had comorbidities (750; 81.3 percent) - usually both (605; 65.6 percent).
Deaths among those below 60 with no comorbidities only accounted for 33 cases (3.6 percent).
Based on Malaysiakini's analysis of the data, Sinovac vaccine recipients account for 710 out of 922 of these deaths (77.0 percent), even though Sinovac vaccine recipients only make up 51.5 percent of fully vaccinated people as of Sept 6 including the 14-day period after the second dose.
In comparison, Pfizer vaccine recipients account for 206 deaths (22.3 percent) while accounting for 43.6 percent of the fully vaccinated population in Malaysia.
In other words, there are 10.11 vaccine breakthrough deaths for every 100,000 people fully vaccinated with the Sinovac vaccine, and 3.47 per 100,000 for Pfizer recipients.
The difference is even starker when looking at the 33 cases involving people below 60 with no history of chronic illness.
Of these, only three (9 percent) had the Pfizer vaccine while the remaining 30 (90.9 percent) had the Sinovac vaccine.
It is unclear whether this is due to differences in vaccine effectiveness, or because the population that received the Sinovac vaccine somehow tended to have more exposure to the disease.
While Sinovac is more widely used in some states, other factors that may affect the efficacy of any vaccine includes living conditions, occupation, socioeconomic status, education level, and Covid-19 awareness, among others.
Nevertheless, vaccine breakthrough deaths are a relative rarity compared to unvaccinated people.
Since the first vaccine breakthrough death up to the most recent one in the dataset, there were 10,211 deaths among unvaccinated people.
This is 11 times higher than all Covid-19 vaccine breakthrough deaths combined.
There were also 3,443 people who received one vaccine dose but did not live long enough to get their second dose and succumbed to Covid-19 during this period.
According to the Health Ministry's definition, a person is considered fully vaccinated after a certain period of time has elapsed after the last dose of the vaccination course, in order to allow time for the body to build up immunity against Covid-19.
For a double-dose vaccine such as those produced by Pfizer, Sinovac, and AstraZeneca, this is 14 days after the second dose.
For single-dose vaccines like those from Johnson & Johnson and CanSino Biologics, it is 28 days after the vaccination.
Meanwhile, in terms of the timing of the vaccine breakthrough deaths, most Pfizer recipients either died or were declared Covid-19 positive around the seventh or eighth week, while deaths or diagnoses after that appear relatively rare as time goes on.
In contrast, 305 (43.0 percent) of Sinovac deaths or diagnoses occurred much sooner at Week 3 and 4 after the second dose and then became increasingly rare after that.
This appears inconsistent with the notion that such deaths are due to vaccine protection waning over time.
However, further analysis may be needed to confirm this, such as by accounting for the timing of Malaysia's vaccine rollout and the varying size of the Covid-19 outbreak in Malaysia.
As for recipients of the AstraZeneca vaccine, only six (0.7 percent) vaccine breakthrough deaths have been recorded – a rate of 0.91 deaths per 100,000 fully vaccinated people. All of them were above 60 years old, and four had comorbidities.
However, this is not to suggest that the AstraZeneca vaccine is superior to the other two vaccines.
Since the AstraZeneca vaccine was introduced relatively late in the National Immunisation Program and had the longest interval between its two doses, people inoculated with the vaccine only began to receive their second doses on July 7 unless some special exemption was granted.
By that time, second doses for the Pfizer and Sinovac vaccines had been rolled out three to four months earlier.
Thus, a more likely explanation for the difference is that people vaccinated with the AstraZeneca vaccine are relatively newcomers to the scene and had less exposure to the disease, compared to Pfizer and Sinovac vaccine recipients who had been trying to dodge the virus for months longer.
The repository contains records of 18,803 Covid-19 deaths from March 17, 2020 to Sept 4, 2021, and includes details of each death such as vaccination status and date, date of Covid-19 diagnosis and death, age, sex, and others. It does not include personally identifying information.
Malaysiakini processed that data for this article by identifying and analysing the deaths, particularly those involving cases where the death or diagnosis (whichever sooner) occurred 14 days or more after receiving the second vaccine dose.
However, about 20 of the records had to be discarded from the analysis due to obvious errors, such as where records show a person had already died when they were vaccinated, or they had died on a date that is still in the future.
There is no data on people who died after receiving the CanSino Biologics vaccine, which was only rolled out recently on Aug 26.
Apart from this and other datasets added to Github that are aimed at researchers and people with high data literacy, Khairy also launched the CovidNow website yesterday to help laypeople better understand Malaysia's Covid-19 situation.
Additional reporting by Andrew Ong.