Super spreaders – a worrying trend


PETALING JAYA: Super spreaders, a generic term describing people who are highly infectious and spread diseases to more secondary contacts than others, are among 10% to 20% of coronavirus cases currently. This strain is the reason for about 80% of new infections, according to researchers.

Public Health Medicine Specialist of University Malaya Medical Centre Associate Professor Dr Rafdzah Ahmad Zaki said super spreaders transmitted the virus to a higher number of cases compared to the others.

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“For Covid-19, the average number that an infected person passes on to is estimated at somewhere between two and three persons.

“In the recent (Sivagangga) cluster in Kedah, the index case has spread the virus to eight persons, ” she said.

Recently, the Health director-general Datuk Dr Noor Hisham Abdullah said there was a high probability that the Sivagangga cluster was from a super spreader strain as the cluster had a faster rate of transmission compared with the nine other clusters currently in the country.

The index case number 8937 had infected 45 people involving three generations of infections in three states since the person responsible for the Sivagangga cluster was first tested positive on July 28.

Dr Noor Hisham said the mutated or “super spreader” strain of the virus might increase the infection rate by more than 10 times.

“In July, we identified a ‘superbug’ and that the virus has mutated to D614G, which is the latest mutation, ” he said, adding that the Institute of Medical Research was studying the virus from the Sivagangga cluster to determine what strain it really was.

“In about a week, we can see the genomic sequence... whether there are mutations (of the virus) or not, ” he said, noting that the spread of Covid-19 in Kedah, Perlis and Penang was now under control.

The Health Ministry’s former infectious disease national head, Datuk Dr Christopher Lee said the D614G variant was becoming the dominant strain around the world.

“This mutation makes the virus more infectious but does not cause more serious illness, ” he said.

The head of Centre for Epidemiology and Evidence-Based Practice noted that any infected person can be a super spreader.

“It doesn’t matter if the person is an index case or infected case in the subsequent generations. Most of the time, these spreaders pass on the virus before they’re symptomatic or have been properly diagnosed, ” Dr Rafdzah said.

The Centres for Disease Control and Prevention (CDC) noted that asymptomatic people contributed to 40% of Covid-19 transmissions.

“It takes an average of six days for an infected person to develop the symptoms, ” CDC noted, by which time the infected person would have come into close contacts with other people and into situations which are favourable for super spreading.

The Malaysian Public Health Physicians Association president added that fast-growing infections in a community was not only caused by a super spreader but in an event or contributing factors that were conducive for super spreading.

Datuk Dr Zainal Ariffin Omar said studies revealed that environmental, social and epidemiological factors can cause super spreading.

A previous study of the severe acute respiratory syndrome (SARS) pandemic revealed that the rate of infection by a super spreader was low to non-existent in the absence of super spreading events.

“Multiple factors can contribute to a super spreading event, namely biological factors such as viral load, behavioural and social factors, which determine the degree of social contact an infected person has and high-risk facilities such as closed spaces with poor ventilation, ” Dr Zainal noted.

“It can also happen at large events with lots of contacts, such as at weddings or during temporary risk of transmission which occurs with loud talking or singing, ” he said.

Many Covid-19 outbreaks worldwide were caused by single events where dozens of people where infected by a single super spreader.

A super spreading event was first reported in Wuhan, China when one patient reportedly spread the virus to 14 healthcare workers in January.

In Seoul, a 29-year-old super spreader caused a new cluster of 54 infections in May when he visited five nightclubs and bars in one night.

In March, a two-and-a-half-hour choir practice session in Washington facilitated the transmission of Covid-19 from a super spreader choir member to 86.7% (52 people) of the others in the room.

Dr Lee noted that despite mutation of Covid-19 resulting in higher transmission of the virus, control measures such as physical distancing, public masking and hand hygiene remained the same while stressing the need for people to strictly adhere to the SOP.

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