The first wave of Covid-19 hit poorer people hardest, according to tests of 405 employees at the Victoria & Alfred Waterfront in Cape Town.

The test volunteers at SA's leading tourist destination came from all social strata. But the 23.7% with Covid-19 antibodies were more likely to live in informal housing, said a team of pulmonologists from the Medical Research Council and Stellenbosch University.

“When stratified by occupation, the largest proportion of the participants who tested positive arose from housekeeping services [cleaners], whereas the participants who worked in management were least likely to test SARS-CoV-2 antibody positive,” the doctors said in the journal PLOS One.

When the team looked at where the employees lived, they discovered that “the highest number of seropositive participants came from the Khayelitsha district”, where half of the 49 volunteers had antibodies.

However, people from Cape Town's Western health subdistrict, which includes the city centre and Atlantic seaboard, “were significantly more likely to test negative and had a seroprevalence of five out of 63 (7.9%)".

Of the 96 people who tested positive, nearly half (46) had been asymptomatic in the six months before the study, which was carried out between August 17 and September 4, 2020, about a month after the peak of Covid-19's first wave in Cape Town.

This led researchers to the conclusion that “there is high background seroprevalence in Cape Town, particularly in people of lower socioeconomic status”.

The latest infection rates in Cape Town support the suggestion that herd immunity, or population immunity' is more firmly entrenched in poorer areas.

In Khayelitsha, which had 71 active Covid-19 cases on Friday, there are only 17 active infections per 100,000 people, compared with 67 in the western subdistrict and 74 in the generally prosperous northern subdistrict. The citywide average is 52 per 100,000.

The researchers, led by Jane Shaw, said they were encouraged by the high number of people with antibodies from poorer and overcrowded areas.

“It could mean that communities less shielded from infection pressure for socioeconomic reasons may at least be less affected during an overwhelming ‘second wave’, barring any significant mutations to the virus which impact the efficacy of neutralising antibodies,” they said.

Khayelitsha's second wave was much less pronounced than in other parts of Cape Town. The number of active infections peaked just 9.2% higher than it did in the first wave. In the city as a whole, the second-wave peak was 179% higher than the first wave's.

The researchers said the poorer employees in their study could have experienced a rapid spread of Covid-19 due to “poor housing conditions, including crowding, and the lack of living spaces that would allow social distancing for several weeks or months”.

They added: “Policymakers need to take into account that it is not reasonable to expect people whose dwellings are barely adequate as sleeping quarters and that lack any recreational space, to practise social distancing to the same degree as the better off sectors of society.

“Furthermore, cultural factors which drive social interactions in these areas must also be understood.

“This study was not designed to investigate alternative Covid-19 control measures, but the social and cultural aspects of socio-economically deprived areas will have to be considered in future epidemics when control measures are planned.

“It would appear that for the Covid-19 pandemic at least, the only likely way to protect the socioeconomically vulnerable is to ensure an early and effective vaccination strategy.”

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