SINGAPORE - A study conducted by the National Centre for Infectious Diseases found that people who contracted Covid-19 at the Bukit Merah View Market and Hawker Centre in June typically touched fruit and vegetables with their bare hands.
The cluster had a total of 94 cases and saw all 182 market stalls closed for two weeks.
The Straits Times looks at what this means for consumers and what added precautions they should take when doing their grocery shopping.
Q: Should I refrain from touching fruit and vegetables or wear gloves when doing so?
A: No, there is no need to refrain from touching them, or to wear gloves when doing so. Professor Dale Fisher, a senior infectious diseases consultant at the National University Hospital, said glove-wearing could, in fact, be an impediment to hand hygiene.
"When wearing gloves constantly, people still touch their handbag, their face and their phone. If there is Covid-19 (virus particles) on the gloves you would be contaminating other places," he said.
Agreeing, Professor Teo Yik Ying, dean of the National University of Singapore's Saw Swee Hock School of Public Health, said that gloves may ironically facilitate the spread of the virus if people become less conscious about hand hygiene, thinking the gloves will protect them.
"It is much better to frequently wash your hands. Carrying a small bottle of alcohol-based hand rub and using it frequently if you are concerned would also be better (than wearing gloves)," said Prof Fisher.
Concurring, Professor Paul Tambyah, president of the Asia Pacific Society of Clinical Microbiology and Infection, said using alcohol-based hand sanitiser is just as good as soap and water.
He added that wearing gloves would not be practical as one would have to change the gloves frequently to avoid cross-contamination.
Q: What are the safety precautions that I should take when choosing fruit and vegetables?
A: Prof Fisher said the most important approach would be basic hygiene. "Wash fruit before you eat it, wash your hands frequently, and avoid touching your face. It's about basic hygiene that really, we learn as children," he said.
Prof Tambyah said that what was striking about this particular study is that buying fish was not identified as a risk factor though people handle fish, in particular the gills, a lot in the market.
"I think the reason is that everyone washes their hands after handling fish. This shows the importance of hand hygiene," he added.
Q: Should supermarkets or wet markets advise people to refrain from picking and choosing vegetables and fruit, or package these items instead?
A: Prof Fisher said it is better if customers do not handle food which has not yet been purchased, though this is hard to implement. However, there will be no need to change the way in which food is managed in wet markets and supermarkets if good hand hygiene is maintained.
Similarly, Prof Tambyah said it would be difficult to change habits of handling or squeezing fruit, although younger people tend to prefer buying packaged or shrink-wrapped fruit in supermarkets.
"Packaging does reduce contamination, but it creates the other problem of packaging waste," he added.
Q: Could fomite, or surface transmission of Covid-19, through the fruit and vegetables be responsible for the cluster at the market?
A: Prof Fisher said that while fomite transmission is possible through touching these items, it is not the most likely mode of transmission.
Rather, markets such as the Bukit Merah one, are more favourable sites for amplification once the virus has been introduced there.
The reasons for this could include crowding, cold surfaces that favour virus survival in the environment, and people not wearing their masks properly, which, too, the study identified.
Prof Teo said the increased infectivity of the Delta variant of the coronavirus could also help to facilitate fomite transmission.
This is because an infected individual actually has a much higher viral load in his body and is thus effectively expelling more virus particles when he talks, coughs or sneezes.
This means that the surfaces coming into contact with these particles will now be contaminated with a higher amount of the virus, making it possible that people are exposed to the virus through fomite transmission.
However, he added that fomite transmission through shared facilities at the market, such as toilets and wash basins, as well as the handling of cash, could also have been possible.