Superspreaders: Why Covid-19 is difficult to curb
Asymptomatic patients who infect large numbers of people derail government efforts to flatten the curve. For those without resources, preventative measures are impractical.
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29 June 2020
As the government eases its lockdown regulations and reopens the economy, the number of Covid-19 cases is increasing rapidly. South Africa has surpassed China, where the outbreak began, in infections.
This is a concern for Minister of Health Zweli Mkhize, who recently published an article in The Sunday Times newspaper detailing a typical day fighting Covid-19. In the piece, Mkhize describes being worried that although people are dying and others are battling to breathe on ventilators, some South Africans are not taking the pandemic seriously. He fears many will realise the magnitude of the virus too late.
“I wonder then, how we get South Africans to comprehend the difficulty of the situation, the extent to which the infection can cause severe illness or death, and the behavioural changes needed to resume economic activity without worsening the spread of the virus?” Mkhize asks.
Superspreaders
According to Cheryl Cohen, head of the Centre for Respiratory Diseases and Meningitis at the National Institute for Communicable Diseases, there are different kinds of Covid-19 spreaders. “Many people infected with SARS-CoV-2 will spread the virus to relatively few other people, but a small number of people can spread the virus to very large numbers of people.”
When someone is pre-symptomatic, they spread the virus without knowing they are ill. They only develop symptoms later. Asymptomatic spreaders do not show any symptoms of Covid-19 but are still able to transmit the virus. A rapid spreader is someone who infects two or fewer people. A superspreader is someone who gives the virus to a large number of people.
“Superspreaders are found all over the world,” says Cohen. “This phenomenon is not unique to South Africa but has been described everywhere where there is Covid-19.” Early this year in South Korea, a superspreader called patient 31 single-handedly caused a spike in cases in the country after attending a church service while positive.
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Superspreaders make it difficult to control Covid-19. But health measures such as wearing masks, physical distancing and restricting gatherings prevent superspreading events. “This is why it is very important that everyone complies with these recommendations,” says Cohen. “These types of measures can have a relatively large impact on reducing spread compared to other viruses.”
The reason one person can spread the virus to large groups is not yet fully understood, says Cohen. “But it is likely that the reasons include characteristics of the person who is spreading the virus. For example, some people may shed [the] virus at a higher level than others, as well as the situation where spread occurs.”
Superspreading often happens in places such as churches and health facilities.
The movement of the virus
A positive coronavirus test doesn’t necessarily mean a person will spread the infection far, says public health specialist Lehlohonolo Majake, but people need to do everything possible to avoid becoming superspreaders, particularly when the virus cannot be managed at home.
“The effects are going to be [drastic] in the public sector in terms of access to the resources to stabilise and treat a patient throughout. We also know that we have limited access to healthcare professionals at this moment … and we know that there is always a struggle of having adequate numbers of human resources both in private and in state facilities.”
Managing the spread of Covid-19 is tricky because we need to rely on people being personally responsible for infecting others or not, says Majake. “Unfortunately, there’s a lot of us [who] might be walking around asymptomatic but [with] the ability [to spread] the virus. The worst thing is to spread it to people who are vulnerable or immunocompromised.”
A superspreader event happens as a result of people’s choices, the environment and policy. South Africa’s alcohol and tobacco bans were implemented to avoid these kinds of events. Alcohol encourages high risk behaviour, Majake says. “We are worried about socialisation without masks. [It] can definitely lead to [events] that … cause superspreading.”
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Smoking affects the critical immuno protective structures in your body. It also burns cilia, the hairs that sweep away bacteria. The smoking ban has been met with much criticism, but Majake says that though some people have been smoking for years, others might just be starting. The ban on cigarettes might deter them.
Also, smokers are not the only ones affected by the habit. “It is not just the primary smoker that is affected by smoking but also the secondary smoker. I used to see a lot of children with upper respiratory chest infections,” Majake says. Most of these children’s parents smoked in the house.
“It is the impact it has … on the people around them [who] are getting sick due to the smoking. We have children who end up with chronic ear infection or chronic asthma because of being exposed to secondary smoking. The damage might have been done on you but you are also perpetuating that damage even further by exposing other people to negative health impacts from your own bad habits,” she says.
However, the Fair Trade Independent Tobacco Association (FITA) has taken the South African government to court over the ban, saying it is irrational and that these products are essential to users. The government countered this argument, saying its decision for the ban was based on scientific and medical evidence. On 26 June, the High Court in Pretoria dismissed FITA’s case, with costs.
The necessary resources
Melissa Myambo, editor of the book Reversing Urban Inequality in Johannesburg, says discussions about the spread of Covid-19 should always be anchored in how unequal South Africa is. Measures such as physical distancing require resources unavailable in shack settlements. Masks are costly, so people reuse the ones they have. Without water, they cannot wash them frequently.
“We know that in most informal settlements, people really struggle to get water. There’s maybe one tap and hundreds of people use that tap. I know the government has been providing some water here and there, but it is never going to be enough … Every time I come home I must wash my mask. If you don’t have access to running water, how do you then sanitise your mask?” she asks.
If a significant percentage of the population does not have the resources necessary to prevent infection, it will be impossible to stop the spread of Covid-19.
