Fourteen public bus or train staff members have caught Covid-19, but none has been found to have infected commuters, the Ministry of Health (MOH) said yesterday.
The MOH, which was responding to Straits Times queries, noted: "There has not been any evidence to suggest Covid-19 transmission arising from a commute on public transport, either involving public transport staff or commuters.
"In particular, MOH's investigations have also not established any epidemiological links between the 14 Covid-19 community cases who are public bus and train staff, and the passengers they may have been in transient contact with."
Public transport ridership during morning peak hours has doubled since the partial lifting of circuit breaker measures on June 2.
Ridership is expected to increase further from today, with more businesses allowed to reopen and small social gatherings permitted.
The MOH said the risk of transmission from encounters involving transient contact such as on public transport is low.
A spokesman said: "The risk of getting infected with Covid-19 is highest in an individual who has had close contact with a confirmed Covid-19 case in work, social or household settings."
The ministry also urged commuters to reduce the risk by keeping masks on at all times and to refrain from talking during their commute.
"Talking increases the expulsion of respiratory droplets, which are a form of transmission for Covid-19," it said.
"As transmission of Covid-19 can also occur through surface contact, commuters should maintain good personal hygiene such as cleaning their hands regularly."
It also urged commuters to use the TraceTogether app, which can contribute to accurate and efficient identification of close contacts of Covid-19 cases, which in turn helps contain the disease.
"This information would also allow for links between confirmed cases to be established in order to identify sources of infection and potential clusters so that relevant public health actions can be taken," it noted.
Meanwhile, public transport operators will continue with stepped-up cleaning regimes as crowds return.
The Land Transport Authority said: "MRT stations and bus interchanges are cleaned at least once every two hours.
"Additional emphasis is placed on sanitising high human contact points like handrails, lift buttons, grab poles and seats."
But one measure that will not be introduced any time soon is the use of a physical barrier to separate bus drivers from commuters.
The LTA referred to a trial of impact-resistant protective screens in public buses in 2018 and noted: "Designs were tested and the feedback from bus captains was that the screens interfered with their field of vision due to glare or reflection issues.
"The trial has ended, but LTA remains open to other measures to protect front-line workers."
Dr Leong Hoe Nam, an infectious diseases expert at Mount Elizabeth Novena Hospital, warned that a lack of evidence on transmission on public transport does not prove that there is no transmission.
"It is very hard to track a person on the train or bus," he said.
"With our SafeEntry system, we cannot tag it to a specific train, and there are not enough downloads of TraceTogether."
Dr Leong said it is now down to the commuters to reduce the risk to themselves.
They can do so by taking public transport during less busy hours, wearing masks properly, not touching their face, not talking and keeping a distance where possible.
Dr Leong said that "it is impossible to have a train serving individuals in isolated bubbles", and train operators can only do so much.