COVID-19 Briefing for 20th May 2020

Notes from a conversation held by Lara Marks with Stephen Baker, professor of molecular microbiology, Jeffrey Cheah Biomedical Centre, Cambridge University on Friday May 15 2020

Healthcare worker screening shows slowing down of COVID-19

We have not had any positive tests for COVID-19 for a week now. This suggests that this is indicative of what is going on in the hospital, which is that they are not admitting that many patients with symptoms linked to COVID-19.

With respect to the testing, it seems that we have broken the back of the disease spread in the community in Cambridge and also now within the hospital. Clearly this is not the case elsewhere. The testing is going to carry on with a view to being able to show the hospital is safe and screening people randomly across the hospital to demonstrate there is no disease. But it looks like for the moment that the peak proportion that we had of 3% of people being asymptomatic is now somewhere closer to nought.

We are still waiting to see what we get back today (May 15). But I think that what is probably going to happen, certainly within Cambridge, is that things will start getting back to normal in the hospital. Because the disease seems to be slowing down or stopping.

At the moment we seem to have an oasis here. Probably all the things we have done with the laboratory and bits and pieces we have contributed have been quite helpful to this situation.

Hospital organisation

The question now is how the hospital will move forward and deal with the risk of the second wave. The key concern for the hospital is opening up things too early in case we get hospital transmission again. For this reason, the hospital wants to maintain some degree of screening capacity. But I get the sense that the hospital staff are very keen to try to normalise things. The hospital has already been divided anyway into green and red areas.

What the hospital will probably start to do is to reopen for elective surgery, if they haven’t already, with a view to then having parts of the hospital open that are known to be coronavirus free. The fact that it has coronavirus free areas is very important. I think that it reflects the fact that the hospital here has done very well in terms of controlling the disease and made some very good early decisions about what they were going to do with respect to sending all the patients away who weren't at high risk. This gave the hospital space and capacity to deal with COVID-19. In fact, the hospital never really became overwhelmed with cases.

The experience in the hospital might also be attributed to the fact that Cambridge is a small city and all its students were sent home early from the university. It also has no high-rise blocks of flats. This presumably means that everybody had space which made it more likely they were to stay at home and not go out.

So overall COVID-19 has not really been a massive problem in Cambridge. Getting things back to normal here is probably going to be quicker than in other places. In part this reflects the way the disease has been dealt with in the city and the way the hospital is planning to reopen and get back to normal.

In many ways Cambridge could be seen as a test case for how other cities manage the disease. But the problem is that not everywhere else has such a small population and good infrastructure or a centralised hospital with such experienced staff.

Dealing with the second pandemic wave

The hospital’s main concern now is what happens next. The question is whether things are opened too early and we get a rebound.

Serological tests

We have been working on the serological tests and are validating the system now. We have a number of known COVID positive patients and some negatives taken from before the outbreak started. On looking at those it appears the tests are working. We can run tests against three antigens - the nucleocapsid (N), the spike (S) and the receptor binding domain at the head of the spike. Our plan is to work with people in the hospital to do longitudinal studies to try and understand seroconversion rates. Seroconversion is the time it takes for the body to develop specific antibodies against the virus which can be detected in the blood. We also want to understand how the seroconversion correlates with protective immunity. We do not have any additional samples to run across a whole load of ELISAs but we have enough to set up our study.

I have been thinking about the serological test a lot. I have now managed to mentally put together all my ideas and found the right collaborators across the university. This coming week we intend to look at the data from the initial assays, work out what we can and cannot do and how we can expand the process so that it can be developed into something a bit more useful that can either serve as a resource for the hospital and/or as an expansive research project.

Collecting scientific data to establish immune response to COVID-19

The serological test is very important for determining where we currently are with COVID-19. At the moment we have a lot of antibody testing going on, but we don’t really know what any of the results mean. What we really need is to collect data on a scientific basis rather than giving everybody kits and seeing whether they have got a response or not. What we need to know is how the antibody works and what it does.

At the moment there are lots of different issues which we don’t really understand. Such as how an exposure or asymptomatic disease may correlate with a different degree of protective immunity. I think that is the next question to explore - is what degree of immunity a person gets if they have had a low level infection or an asymptomatic infection compared to whether you have had a full-blown infection of COVID-19 disease. Essentially what we want to establish is to correlate the amount of exposure to the kind of antibodies produced and the number of antibodies produced.

I know a paper has come out this week on T cells and their response to the virus, although I have not yet read it. I am not very familiar with T cells, but it does look like there is a T4 response which may or may not be associated with the production of antibodies.

Once we have got the assays working and linked this with the genomics work that is going on the next step will be how we then try and develop assays to understand exposure, seroconversion and protective immunity.

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