A New Coronavirus

2019-nCoV is having an effect that most will have heard of. It is apparently milder than some related viruses, such as SARS, which had a mortality rate of 10%, but that might be premature because the new virus has caused a very large number of seriously ill people, and nobody knows what will happen to them. So far, the probability of death appears to be around 3%, although a number of those are through people who had poor health anyway. Unfortunately, it appears to spread at a dizzying rate, and so far the number of patients appears to double every six days. It appears to have a period of about 12 days when it is asymptomatic, but it remains contagious. Most people will know about the effects of mild contagious coronaviruses. The common cold is caused by over 90 different viruses, the majority of which belong to the rhinovirus family, but coronaviruses participate in a good percentage.

This virus almost certainly came from animals, probably a bat, but when and how are uncertain. The genomic sequence of 2019-nCoV is 96.2% that of a bat coronavirus, and 79.5% is identical to sequences found in SARS. The Huanan Seafood Wholesale Market in Wuhan, which also sells animals as well as fish, may be the origin of the outbreak as the earliest patients had visited it, and 33 environmental samples from the Western end of the market, which is where the animals were sold, contained the coronavirus. However, the first patient apparently had no contact with this market, so it is possible it started elsewhere and infected the market. Genomic sequencing, which involves counting mutations since entering the human population, suggests the virus began spreading in mid November, 2019.

So, what can be done? At present, the best approach is containment, but whether this is possible when it takes two weeks for symptoms to appear is another matter. If it works, in a few months everybody will wonder what the fuss was all about. If containment fails, it appears to be as contagious as the common cold, and who hasn’t had one of those? One calculation has suggested there could be up to fifty million dead through it. Most would say that is unduly pessimistic, but is it? If there is any good news, it is that the number of reported cases in Wuhan have had about three days of falling. We hope the decline is real and not a consequence of poor reporting.

For current patients and those over the next year, we need something ready to go, and fully approved for use. That suggests trying drugs with antiviral properties. At this point we do not know whether any will work, but if used on patients with the virus, the argument is it is preferable to attempt to do good. In Wuhan, they are already trying a randomized controlled trial of two drugs that target the protease enzyme used by HIV to copy itself. These drugs apparently gave beneficial results against SARS, which is promising. The drug remdesivir, made by Gilead Pharmaceuticals, is a possibility. It interferes with the viral polymerase enzyme, and it has shown activity against every coronavirus tested so far. When combined with interferon it slowed viral replication in MERS-infected mice. (MERS is another coronavirus.) Another US biotech Regeneron is trying to develop monoclonal antibodies; it has previously managed to develop them that were effective against ebola and MERS. 

The next most obvious approach is to develop a vaccine, but historically there has never been a vaccine developed fast enough to have a significant impact on an emerging virus. Historically, vaccines were based on the concept of injecting dead virus into the body to stimulate the immune system, but this is not the current approach. The Chinese got proceedings started by publishing the genetic code of the virus, which was truly impressive work given how quickly they did it. One approach is to convert viral sequences into messenger RNA, which causes the body to produce a viral protein that triggers immune responses. Another approach, at the University of Queensland, is to try to develop a vaccine made of viral proteins grown in cell cultures. Another approach is to make a string of RNA that corresponds to a section of the coronavirus. Thus there are a variety of approaches, and the question then is, will they work?There is also the question, will they work fast enough? Suppose we developed one? It is inconceivable this could be done in less than three months, at which time there would need to be clinical trials. These would take several weeks, and that would have to be followed by a period of six months where it was determined whether there were any adverse effects. That would have to be followed by an extended period where it was examined whether the vaccine actually works, and the net result of this is that it would take over a year at the very least to decide whether we had a working vaccine. Then it has to be manufactured. A vaccine is our only defence if we cannot contain it and it becomes endemic. In the meantime, the scientific community is working; apparently there are at least 77 scientific papers made public on it since the outbreak became declared.

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Google photo

You are commenting using your Google account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s