The US envoy to China has called on the country to be "more honest" about the origins of the Covid-19 virus.

His comments come a day after US media reported a federal agency had found the pandemic probably started from a laboratory leak in Wuhan.

China's foreign ministry hit back that the global outbreak's origin "was about science and should not be politicised".

Washington-Beijing ties have been under strain since the US shot down an alleged Chinese spy balloon this month.

Ambassador Nicholas Burns told a US Chamber of Commerce event on Monday that China needs to "be more honest about what happened three years ago in Wuhan with the origin of the Covid-19 crisis".

US media reported on Sunday that a report from the US Department of Energy had concluded in a classified intelligence report with "low confidence" that the virus was accidentally leaked by a laboratory.

The energy department had formerly said it was undecided on how the virus began.

Other US agencies have drawn differing conclusions, with varying degrees of confidence in their findings. The FBI in 2021 concluded with "moderate confidence" that the virus leaked from a lab.

Other studies suggest it made the leap from animals to humans at Wuhan's Huanan seafood and wildlife market.

An unclassified report released by the US top spy official in October 2021 said that four US intelligence agencies had assessed with "low confidence" that it had originated with an infected animal or a related virus.

White House national security spokesman John Kirby said on Monday there was still no firm finding either way.

"There has not been a definitive conclusion and consensus in the US government on the origins of the Covid-19 pandemic," he told reporters when asked about the energy department's reported determination.

For most food products tested there was a "significant drop" in the levels of virus over the first 24 hours.

But in some cases traces survived for about a week, the University of Southampton team found.

"For a highly infectious agent such as Sars-Cov-2, which can be transmitted through touching contaminated surfaces and then the face, these findings are highly noteworthy," they say.

"The public may be interested in the finding that virus may persist in an infectious state, on foods and food packaging surfaces, for several days under certain common conditions."

But they add that there is no need for shoppers to take extra precautions when handling food - other than washing your hands before preparing and eating it, and rinsing fresh produce to help to remove any contamination on the surface.

They picked foods often sold loose at grocery, deli or bakery counters, such as apples, peppers, cheese, ham, olives, crusty bread and croissants.

The packaging tested included drink bottles, cartons and cans.

The amount of virus they applied was designed to simulate how much might land on food if someone who was infected coughed or sneezed near it, for example, because Covid is spread by respiratory droplets.

Breathing in infected droplets, rather than touching infected surfaces, is still the main way people catch Covid.

Anthony Wilson, microbiological risk assessment team leader at the FSA, said: "In the early stages of the pandemic, we didn't know much about how the virus would survive on different food surfaces and packaging, so the risk assessment was based on a worst-case assumption.

"This research gives us additional insight into the stability of coronavirus on the surfaces of a variety of foods and confirms that assumptions we made in the early stages of the pandemic were appropriate, and that the probability that you can catch Covid via food is very low."

Covid: Woman caught virus twice within record 20 days

A 31-year-old healthcare worker caught Covid twice within 20 days - the shortest-known gap between infections, Spanish researchers have claimed.

Tests show the woman was infected with two different variants - Delta in late December and then Omicron in January.

This shows that even if you have had Covid before, you can still be infected again even if fully vaccinated, the researchers say.

Based on that definition, health officials say nearly 900,000 people in the UK have potentially been infected twice with Covid up to the start of April.

It is difficult to pin down an exact number, because only whole genome sequencing can confirm the infections are caused by different strains, and very few positive tests go through this process.

The Spaniard did not develop any symptoms after her first positive PCR test, but less than three weeks later she developed a cough and fever which prompted her to take another test.

When the tests were analysed further, they showed the patient had been infected by two different strains of coronavirus.

In a presentation at the European Congress of Clinical Microbiology and Infectious Diseases, study author Dr. Gemma Recio said the case highlighted that Omicron can "evade the previous immunity acquired either from a natural infection with other variants or from vaccines".

She said: "In other words, people who have had Covid-19 cannot assume they are protected against reinfection, even if they have been fully vaccinated.

"Nevertheless, both previous infection with other variants and vaccination do seem to partially protect against severe disease and hospitalisation in those with Omicron," added Dr Recio, from the Institut Catala de Salut, Tarragona in Spain.

The initial emergency of Covid may feel like it's over, but millions of people are still suffering from ongoing symptoms known as long Covid. So are we any closer to understanding the causes of this sometimes debilitating condition or to finding the best way of treating it?

Most people who catch Covid don't become severely ill and appear to get better relatively quickly. We do not know if there are any long term or long-lasting health effects, such as a lower life expectancy, reduced immune system response to other sickness. We are all guinea pigs, so to speak, and only time will tell what the long term effects of having Covid, or of having Covid more than once, are. 

Some people have long-term problems after recovering from the original infection - even if they weren't very ill in the first place.

What are long Covid symptoms?

Long Covid isn't fully understood, and there's no internationally-agreed definition - so estimates of how common it is, or what the main symptoms are, vary. These can be defined as symptoms that continue for more than 3 to 4 months which cannot be explained by another cause.

These can include:

• extreme tiredness
• shortness of breath, chest pain or tightness
• problems with memory and concentration ("brain fog")
• changes to taste and smell
• joint pain

This pattern will be familiar to many with long Covid. The core experience of long Covid revolves around three principal symptoms: fatigue, brain fog and muscle pain. But there is a long list of rarer symptoms covering almost every bodily function ranging from digestive problems to night sweats and depression to hair loss.

Humans breathe principally through their noses, so it is imperative to mask the nose as well as the mouth. It is equally imperative to be masked at all times in crowded indoor areas like public transportation, supermarkets, schools and shops, as well as in crowded outdoor areas where social distancing of at least 2 meters in all directions is not possible - like on crowded sidewalks and in crowded areas of parks and public squares. Let's encourage everyone to shame improper mask wearers or those not wearing a mask when they should by uploading their photo and mentioning where and when they were not properly masked at No-No.net.
(* 2023 - I took this site down since it's moment had passed and no-one listened, and I didn't have the money to keep it up!)
This should help encourage people to behave correctly for their own welfare as well as the welfare of others - and start wearing masks properly when needed!

Ever since the coronavirus reached the U.S., officials and citizens alike have gauged the severity of the spread by tracking one measure in particular: How many new cases are confirmed through testing each day. However, it has been clear all along that this number is an understatement because of testing shortfalls.

Now a research team at Columbia University has built a mathematical model that gives a much more complete — and scary — picture of how much virus is circulating in our communities.

It estimates how many people are never counted because they never get tested. And it answers a second question that is arguably even more crucial — but that until now has not been reliably estimated: On any given day, what is the total number of people who are actively infectious? This includes those who may have been infected on previous days but are still shedding virus and capable of spreading disease.

The model's conclusion: On any given day, the actual number of active cases — people who are newly infected or still infectious — is likely 10 times that day's official number of reported cases.

The model has not been published or peer-reviewed yet, but lead researcher, Jeffrey Shaman, an infectious disease specialist at Columbia University, shared the data exclusively with NPR. Here are more of the startling takeaways.

Missed cases remain a massive problem

To come up with their bottom line estimate, the researchers' first step was to estimate, for each day of the outbreak so far, how many people actually became infectious. Then they compared that with the number who got tested and counted as a confirmed case.