Boo: Are our Covid-19 management guidelines too loose?

 

Johor DAP committee member Dr Boo Cheng Hau has questioned whether current guidelines issued by the Health Ministry (MOH) could have partly contributed to the rise in Covid-19 cases.

In a Facebook post today, Boo noted that current Health Ministry guidelines still allow asymptomatic Covid-19 patients to be discharged on the tenth day of their quarantine without retaking a PCR test.

“There are unknown numbers of patients with positive PCR tests with cycle threshold values (Ct) of 20s after 10-14 days of quarantine.

“Many studies have shown that, if Ct values are less than 35, it indicates there is a high possibility (the patient is infectious).

“Has this loose criterion of management contributed partly to the rampant spikes in Covid-19 cases too?” asked Boo, who is also a general practitioner and Covid-19 survivor.

However, he also noted that a Covid-19 patient’s PCR test could remain positive for up to three months without being infectious.

 For the record, Ct value refers to the number of PCR cycles needed to ‘amplify’ a swab sample so that the virus in the sample can be detected by the PCR machine’s sensors.

If fewer cycles are needed to obtain a positive result, it implies the virus is present in the sample in greater numbers (i.e. high viral load).

However, PCR tests cannot distinguish between a ‘live’ infectious virus and a ‘dead’ virus that is no longer infectious, making it a crude proxy for determining a patient's viral load and potential infectivity.

Another way to determine infectivity is to attempt to grow the virus on Petri dishes using swab samples collected from patients.

Previous studies had found that the virus cannot be grown from samples that are collected from Covid-19 patients if the sample is collected more than 10 days from the date of diagnosis or onset of symptoms.

This includes patients who continue to test positive for Covid-19 after that point, implying that the virus is no longer viable in such patients even though there is detectable viral material present.

The finding - backed by real-world contact tracing data - is the basis for the 10-day quarantine period. However, it is unclear whether this still holds true when it comes to the Delta variant that is now prevalent in much of the world.

Limited surveillance breeding newer variants?

Meanwhile, Boo questioned whether Malaysia’s limited genomic surveillance is inadvertently contributing to the emergence of newer, deadlier Covid-19 variants.

He claimed that the country’s Covid-19 genome sequencing rate is only 0.15 percent of all PCR samples.

This is compared to other countries such as Singapore (6 percent), UK (7.4 percent), Iceland (10 percent), New Zealand and Australia (40 to 50 percent), he said.

“Has our extremely low genome sequencing rate contributed to the emergence of more transmissible and deadlier new variants of concern than the Delta variant, unknowingly?” he said.

Genome sequencing is the process of decoding genes to learn more about the virus.

This allows scientists to identify the virus and monitor how it evolves over time into new variants, using this information to better understand how it might impact health.

According to the genetic repository Gisaid, Malaysia only sequenced and shared genetic data on 0.085 percent of its Covid-19 cases in the last 180 days – much lower than the figure provided by Boo.

This reflects a broader trend of low sequencing rates across most of Southeast Asia, which ranges from zero percent in several countries and 0.83 percent in Cambodia.

A notable outlier is Singapore, which sequenced genomic data from 51.2 percent of its Covid-19 cases and shared it with the scientific community, making it the highest percentage in the world.

Health Minister Dr Adham Baba had previously announced an RM3 million initiative to boost Covid-19 genomic surveillance in the country, with the aim of sequencing 3,000 samples in three months from August to September.

A Flourish chart

 - Mkini