Update on COVID-19: part 15, keep a distance

In my country we stopped shaking hands, because of SARS CoV-2, and in a large region people are asked to work at home. Is that justifiable, in light of the evolving pandemic? The answer is YES, according to two publications that appeared yesterday. Continue reading

Update on COVID-19: part 14, the changing picture

Where the world is gradually (or instantaneously) facing the COVID-19 reality, China claims victory. Yet, it ain’t over till it’s over, and many fear a rebound once daily life has returned to its normal practices and contact patterns. In the meantime our Chinese colleagues keep on producing very impressive epidemiological studies. Such as this one, published today. Continue reading

Update on COVID-19: part 13, it giet oan?

In February many in my country just want to hear three words: “it giet oan”. This means that the famous eleven city ice-skating race will actually happen. Since 1909 this occurred 15 times (last time in 1997), as it needs about three weeks of continuous frost. No chance for that this year, but the words must have crossed many clinical microbiologists’ mind this weekend when the news on SARS-CoV-2 from Italy unfolded. Continue reading

Update on COVID-19 caused by SARS-CoV-2; part 12

part from its new name, nothing really happened in the last week. New confirmed cases per day remained high, seemed to decline somewhat until it became clear that there was shortage of testing capacity. Definition adapted, and then the numbers of infected patients in the affected Chinese regions exploded. So, one question answered from previous blogs: it’s big in China and we may (still) not know everything that is happening there (or in some other countries). Continue reading

Update on 2019-nCoV: part 10

The 2019_CoV outbreak remains as interesting as the House of Cards once was (until it was bypassed by reality). After the gold rush for R_0, last week was devoted to the question on silent transmission; yes or no. Tuesdays’ story had an unexpected follow-up today, but the true clifhanger is a new study published yesterday. Continue reading

Update on 2019-nCoV: part 9 – ‘silent’ transmission

A rude awakening this morning: “Study claiming new coronavirus can be transmitted by people without symptoms was flawed” was reported in Science. This is the patient described by German colleagues in NEJM and by Jon in the previous blog post.

The story in short: An index patient (a woman from Shanghai) was visiting Germany for business, and managed to transmit the coronavirus to two patients, who subsequently transmitted the virus to two other colleagues, before symptoms arose (in the index patient). The story was reported by hospital physicians from Munich and a virologist from the Charité hospital in Berlin (where the famous Robert Koch once worked).

In Science: “The Robert Koch Institute (RKI), the German government’s public health agency, has written a letter to NEJM to set the record straight, even though it was not involved in the paper.”

The researchers in Munich didn’t actually speak to the woman before they published the paper. “Afterward, however, RKI and the Health and Food Safety Authority of the state of Bavaria did talk to the Shanghai patient on the phone, and it turned out she did have symptoms while in Germany. According to people familiar with the call, she felt tired, suffered from muscle pain, and took paracetamol, a fever-lowering medication.”

When reading this I recalled two dreams I had this night.

Somewhere – in a not-mentioned country – physicians were very excited as the first patient with disease X had fallen in their lap. “Let’s first send this to NEJM and then contact our public health officials, otherwise they run away with it.” The day after – at the other site of the country – the NEJM fell on the floor in the oval office of the head of public health – responsible for the nations’ faith. He/she contacted the index and found out that she – in retrospect and after 20 times repeating the same question – admitted that “yes, she felt tired, had some muscle pain and took a paracetamol”. “That’s it”, he/she shouted, “this is the perfect call”, “READ THE TRANSCRIPT!” and called Science.

The other dream: Somewhere – in a not-mentioned country – physicians were very excited as the first patient with disease X had fallen in their lap, and they immediately contacted the head of public health – responsible for the nations’ faith. “Let’s first send this to NEJM and then contact the index. Might give us 2 citations in NEJM.” The day after the NEJM fell on the floor in the oval office of the head of public health and he/she contacted the index and found out that she – in retrospect and after 20 times repeating the same question – admitted that “yes, she felt tired, had some muscle pain and took a paracetamol”. “That’s it”, he/she shouted, “this is the perfect call”, “READ THE TRANSCRIPT!” and called Science.

Then my alarm went off, and I couldn’t dream of other, more realistic scenarios.

The big question now is whether our view on the transmission dynamics of this outbreak should change with this new information. The point of silent transmission, i.e. before symptoms occur, is that it will be more difficult to identify infectious persons and isolate them in time to interrupt transmission. The symptoms reported in retrospect (when knowing of being indeed infected, susceptible to recall bias!) were “tiredness and muscle pain”. Cough and fever are not mentioned. If this is what it is, then this woman might still have been identified of being at risk for 2019_nCoV infection in Germany, simply because she came from China. Yet, in Wuhan this would probably not be recognized as a risk, necessitating isolation. And the same would hold if sustained transmission occurs in other countries.

So, this information sheds new light, and addresses the definition of being asymptomatic. If symptomatic would be defined as “symptoms that allow someone to be recognized as infected and to be isolated in time to prevent transmission”, I think, this subject would be considered asymptomatic.

The letter from RKI has not yet been published. The Science reporting is based on someone who was in the room during the phone call (sweet irony).

Disclaimer: if the letter describes a feverish Chinese woman coughing continuously, I immediately change some of my views.

Update on 2019_nCoV outbreak part 7

We live in fascinating times. Within a week R_0 has be become a fashionable topic to discuss at cocktail receptions, science has transitioned from old-fashioned hidden peer review to open review on preprint servers and China is doing the largest experiment in infection control ever. And since tonight we have a public health emergency of international concern (PHEIC).

I’m very impressed by the actions in China, so far. It looks as if they very rapidly (within a month) recognized a cluster among patients with severe pneumonia in which no pathogen was detected (which happens in about 50% of these patients). Then, within a month they identified the cause of these infections, sequenced it and found the receptor for the virus, and immediately shared all information.

They also must have realized around that time that they were dealing with something very transmissible, which was subsequently confirmed by the many R_0 estimates. I think most agree that R_0 is somewhere between 2 and 3, but what does that mean for infection control?

R_0 is determined in the very early phase of the epidemic, when all subjects are susceptible to infection and when preventive measures have not been started. In that phase the virus is transmitted in a certain network, in this case a city of 10 Million, in which many contacts occur that could lead to successful transmission. When the outbreak is recognized, many mechanisms start that reduce transmission. In hospitals protective measures are taken and outside hospitals people start changing their behaviour. For instance, they avoid public transport and mass gatherings and stay at home. From then on it is better to name R an effective R value, which is of course less than R_0. Infection control aims to bring the effective R value below 1, and keep it there. The latter is not to be underestimated: if the original behaviour is resumed at a time that the virus is still circulating, the epidemic may rapidly speed up again. As may happen if the virus escapes to another – unprepared – network.

How can we see whether R declines? Just look at the epidemic curve (from which R is derived). As long as the number of newly infected subjects per day increases, R is >1. So, we want to reach the downhill slope of the epidemic curve, as fast as possible.

How to do that? Every epidemic dies out if the number of susceptibles declines. That is when a large part of the population has become immune, either through vaccination, surviving the infection (with immunity), or protective therapy (not really immune, but similar effect). The proportion of the population needed in this category is around 60-70% with this R_0, which is unlikely to happen soon for this virus. This leaves classical measures to reduce transmission with at least 60-70%.

China has the laudable ambition to do this. For that they have quarantined millions, which is a daunting task. Imagine Ursula van der Leyen (chair of the European commission) quaratining London, Paris, Amsterdam and Madrid.

Within the fence almost all transmission must be stopped. How long will this take? Well, if all transmission (100%) is prevented as of tomorrow, new infections will occur for at least a week, due to the incubation period. If interruption is less effective, say 70%, it will take (much) longer. The effectiveness to stop transmission outside hospitals requires isolation of infectious persons during their infectious period, which might start before being symptomatic. So, it may take some time before the outbreak is controlled sufficiently to open the fences without risks of the epidemic starting all over again. Question is how long they can keep the gates closed.

So, let’s carefully follow the epidemic curves, and hope that they are accurate and not compromised by reduced case notification due to shortness in testing capacity or collapses of hospital systems, which may give a false-positive reassurance. If China succeeds in controlling this outbreak, their efforts could be placed next to the Chinese Wall, as another Wonder of the World.