Factbox: Can frozen or chilled food spread coronavirus?

Scanning electron microscope image shows SARS-CoV-2 (round gold objects), also known as novel coronavirus

(Reuters) - While the origin of a spike in coronavirus infections linked to a big wholesale food market in China's capital is not known, officials have warned against eating raw salmon after the virus was discovered on chopping boards used for imported salmon.

Below are comments from health officials, doctors and other experts on the risk of infection from eating or handling frozen or chilled food.

WU ZUNYOU, CHIEF EPIDEMIOLOGIST OF CHINA'S CENTER FOR DISEASES PREVENTION AND CONTROL

Wu told state media over the weekend that the virus can survive on the surface of frozen food for up to three months and his agency "highly suspects" contaminated goods were the source of the latest outbreak.

But he said more investigation was necessary, as it was possible infected people arriving in Beijing could have spread it.

JIN DONG-YUN, VIROLOGY PROFESSOR AT THE UNIVERSITY OF HONG KONG

Virus contraction via frozen food usually involves viruses such as the rotavirus and hepatitis A virus being transmitted through the gastrointestinal tract.

It typically happens with contaminated food consumption, which is not the route through which respiratory viruses infect people. SARS-CoV-2 is not known to be transmitted via consumption of contaminated food.

It requires further investigation to determine whether a person can contract the coronavirus either by touching contaminated surface or via direct food consumption.

EYAL LESHEM, DIRECTOR OF THE CENTER FOR TRAVEL MEDICINE AND TROPICAL DISEASES, SHEBA MEDICAL CENTER, ISRAEL

There is no evidence of novel coronavirus transmission through food, food containers or food packaging. The vast majority of infections occur due to close contact with infectious patients.

Infection from fresh food like meat and fish may occur if a kitchen worker or waiter goes to work while ill and touches the food, thus transmitting the virus.

We think risk from frozen food is very low when proper food preparation guidelines are kept.

PAUL TAMBYAH, PRESIDENT OF THE ASIA PACIFIC SOCIETY OF CLINICAL MICROBIOLOGY AND INFECTIOUS DISEASES

A group from Hong Kong has shown that the survival of the virus is significantly altered by temperature and humidity. It has said in a preliminary report that the virus can survive for only a day at 37 Celsius (98 Fahrenheit), compared with a week at 22C (71F) and more than two weeks at 4C (39F). The data relates to a solid inanimate surfaces, not meat.

I am a little skeptical that this outbreak in the market was actually related to a source thousands of miles away carried through frozen food. It is probably more likely that there was an individual who may have been heavily infected with the virus who spread it through the market but we cannot be sure until this individual is found, which may never happen.

This virus has surprised us many times, unfortunately.

OM SHRIVASTAV, DIRECTOR, INFECTIOUS DISEASES, JASLOK HOSPITAL, MUMBAI

We've known this virus for less than five months. It is a little premature to say that this particular coronavirus can or cannot withstand changes in its environment.

Based on the evidence alone at this time, I'm not aware of a food-borne transmission.

DALE FISHER, SINGAPORE-BASED DISEASE EXPERT AND CHAIR OF THE GLOBAL OUTBREAK ALERT AND RESPONSE NETWORK COORDINATED BY THE WORLD HEALTH ORGANIZATION

If we want to store virus, we freeze it. So if virus is packed with frozen product then it would survive. We normally talk about less than a week, but we know that the colder it is, the longer it will last ... That's part of the theory around why the virus is more contagious in winter.

So you bring the surface down ... in a refrigeration unit, tied to the fact that we know there has been outbreaks in meatpacking plants etc, it is possible.

(Reporting by Roxanne Liu in Beijing, Rocky Swift in Tokyo, John Geddie in Singapore, Sangmi Cha in Seoul and Sachin Ravikumar in Bengaluru; Writing by Miyoung Kim; Editing by Robert Birsel)