There was an interesting report in the Edge on 8/8/2021 regarding the number of new cases of Covid diagnosed in the preceding 24 hours with the breakdown by categories and vaccination status. The figures quoted give some useful information regarding the ongoing surge of the Delta variant. The data from the Edge –
Newly Diagnosed cases of Covid-19 in Malaysia. 8/8/2021
Clinical Category on Day of diagnosis (D1)
Total cases diagnosed in preceding 24 hours
Individuals who have taken one or two doses of the Covid Vaccine
The Edge article also mentions that the 18,688 individuals found positive for Covid were from a cohort of 143,476 individuals tested. According to government figures, 47.47% of the Malaysian population had received at least one dose of the vaccine as of 8/8/2021. It is likely that 52.53% of the 143,476 persons tested or 75,367 individuals would have been unvaccinated while 68,108 would have had received at least one dose of a Covid vaccine1.
Incidence of Covid infection by Vaccination Status
Vaccine Status of individuals tested
Number positive for Covid 19
At least one dose of vaccine
The table above demonstrates that the rate of infection among the persons who were unvaccinated is almost 3 times higher than for those who had received at least one dose of the Covid vaccine. The risk of contracting Covid is about 65% less for the vaccinated compared to those who were not vaccinated (and these figures are statistically significant2). And we must bear in mind that more than half the number of the vaccinated group were people who still hadn’t taken the second dose of the vaccine. In other words the protection against infection given by the Covid vaccines would be much more than the 65% figure calculated above once both doses are administered. This is the sort of information that we need to share with our relatives and friends who are still hesitating about getting the vaccine – that local data mirrors the experience of other countries and that vaccination markedly reduces the risk of getting infected.
One could use the data in the Edge report to calculate the differences in the incidences of Category 4 and 5 cases between vaccinated and unvaccinated individuals, and the figures would be quite impressive. But I will not proceed to that because that would not be quite honest. We all know that many patients in category one and two on the day of diagnosis will deteriorate to categories 3, 4 or 5 over the next 2 weeks after diagnosis. It would be more appropriate to calculate the protection conferred by vaccination against ICU admission by looking at the categorization of the cohort on Day 14 after diagnosis3. I believe it is important to be scrupulously honest with the public. That is the best way to build credibility and trust.
One other bit of data I would like to highlight from the Edge article is the test positivity rate of 13% – in other words, 13% of the persons tested were positive. This, according to the WHO, indicates that we are not doing enough testing. Testing numbers are determined to a large degree by how thoroughly contact tracing is carried out for all recognized cases. Contacts staying in the same household as the index case would have the highest positivity rate. Then would come the contacts who visited the family, or who were visited by the index case. The people who crossed paths with the index case outside the house would have even lower positivity rates. So as you test more people, the cumulative positivity rate would come down. The WHO has suggested that a positivity rate of 5% would mean that contact tracing has been adequate.
However it is not be possible to do proper contact tracing when the number of new cases exceeds a certain number – for Malaysia the threshold might be around 5000 cases per day. For before the MOH teams can complete tracing the contacts of today’s cases they will be given another set of cases to look into. The capacity of the system to trace and quarantine contacts has been breached in Malaysia. What this means is that there are now many individuals out there who are infected but are at present with minimal or no symptoms, and have not been diagnosed or asked to quarantine. They can unknowingly pass the infection to others. This is why many of the cases being diagnosed now are termed “sporadic” – they cannot be linked to any recognised cluster. The take home message is this – at this point in time, there is significant transmission from infected individuals who have not been identified and quarantined. So it is crucially important that we physically distance, double mask and reduce our exposure to crowds even though we might have taken both doses of the vaccine.
There are still many people in Malaysia who are reluctant to take the vaccine. There are others who aren’t too serious about physical distancing or wearing their masks properly. If the MOH could release data pertaining to the vaccination status of newly diagnosed cases by state, the number of cases by category on day 14 and the test positivity rate by state on a daily basis, journalists and analysts could use the data to present a clearer picture of the how the pandemic is unfolding. This will induce more people to comply with the SOPs and help in the control of Covid 19.
Dr Jeyakumar Devaraj
Parti Sosialis Malaysia
1. This is an assumption on my part.
2. Statistically significant means that there is less than a 5% probability that this magnitude of difference could show up by chance.
3. The MOH and the STAR paper have been highlighting the low numbers of category 3, 4 and 5 in newly diagnosed cases of Covid 19. This is, I think, an attempt to put a positive spin on the bleak situation. But I think it is counter-productive. If we want people to practice all the SOPs to contain the spread of Covid, then we should not misrepresent data to make the situation look much less serious than they actually are.