COVID-19 Briefing for 1st May 2020
Notes from a conversation held by Lara Marks with Stephen Baker, professor of molecular microbiology, Jeffrey Cheah Biomedical Centre, Cambridge University on Monday 27th April
Today it feels like it should be Friday, but it is only Monday. Everyone is exhausted. We are all a bit ‘covided’ out to be honest. We all really need a break.
Data from COVID-19 testing of healthcare workers
As of last Friday we had done over 1000 tests on healthcare workers at Addenbrooke’s Hospital. A group of us have been working to get the data together from those tests and interpreting what the results mean. As far as I am concerned the data is not scientifically ground breaking. But it is important because it gives us a sense of where we are and it is going to be critical for how to control the virus. Until now no one else has put together data from the screening of asymptomatic healthcare workers and we are now at that point where we have good data. The data has been written up in an article that is soon going to be submitted to BioRx.
We have linked up with the hospital’s occupational health division who have identified a lot people with the virus. We know the positive baseline in the symptomatic patients and people who work inside the hospital. This data is going to be used to infer them rolling out healthcare screening across the country.
Serological testing for the immune response
In terms of the serological tests we are still waiting for safety approval to do that. We have antigens and some positive sera from people that were Covid patients and we have had some negative sera from a bioresource that we requested at the back end of last year. We have coated some plates but we have no antibody preparations as yet. So we have got everything set up and we are just waiting for approval for us to handle the positive samples so we can go ahead.
We are aware of the reports about people not developing strong antibody responses to COVID-19. This might reflect where the person is in the infection process. They are probably not likely to show much in the way of an immune response in the early onset of the infection, but this is likely to improve later on. That’s one thing. But also it may depend on the antigen used in the test as well. We have several antigens to try out. We have got N, we’ve got the receptor binding domain and the full S antigen. Depending on what other people are using, we may have a better idea of what antibody responses are being generated and we are going to link that up with some sort of functionality as well. This means looking at the functional response of the antibody to the virus.
ICU patients with COVID contracting bacterial infections in hospital
We are still working on rolling out the diagnostic testing in the ICU. We have had about 30 samples now and we are running the PCR. We have detected some patients with COVID and some who are negative. Almost all the COVID patients we do not know quite how long they are going to be in the ICU for and what that looks like. But almost all of them have got some degree of co-infection. Obviously, the patients are not very well, they are on ventilators. Based on bronchial washes done with the patients we have identified a high proportion of them - I think all except one - have got some sort of bacterial infection in their lungs.
A bronchial wash is a procedure that involves pushing sterile saline into the lungs and sucking it back out again. The aim is to try and wash out the lower lung alveoli to pull out what is left to get a sample. That enables us to see what is infecting the lower lungs.
An interesting observation is in one case where a person underwent a tracheal aspirate procedure, a bronchial washout taken from the site of a tracheotomy, indicated they were COVID negative. Then the day afterwards the patient was given another bronchial lavage in the lower lungs which showed that it was positive. This suggests that there may be a different degree of infection between the upper and lower respiratory tract as well.
The observation illustrates that where you take the sample from is going to affect the result. The patient is likely to have contracted the bacterial infection after they were put on a ventilator because they had COVID. It is likely they had respiratory symptoms, they then went into respiratory distress, they were then put on a ventilator for some time, and then while they were in hospital they picked up another type of bacterial infection. Having such an infection is not going to help the patient recover from COVID.
This is why the diagnostic test we are developing is so important. It can help identify the other type of bacteria so they can be treated for that and get on top of that infection so that it does not make them worse. That will help give them a fighting chance to recover from COVID.
It will be interesting to know when we get all the information together about what the patients had and what their progression has been and their outcome in terms of whether people do worse or better if they have other pathogenic infections. There is probably a chance that if someone is on ICU for a long period for COVID they will get additional respiratory type infections associated with drug-resistant organisms. This is an important issue going forward, because if we start to get to grips with COVID we could go back to square one because of having to treat drug resistant bacteria.
It is for this reason that we want to get a monoclonal treatment for drug resistant infections. I would love to get back to working on this project but it will take a good few more weeks before that can happen.
Children and COVID-19
We have been doing some work with the Children’s ICU and we haven’t seen many cases there. There have been one or two positive cases in the unit. There may be some questions about kids getting infected with the virus, but it is not common.
Working out how to go forward
We are currently working on where we go from here in terms of handing over what we have been doing to someone else so we can get back to normal. Obviously we still want to make a contribution to the efforts to deal with COVID-19 and get the hospital back to normal but ultimately we want to do our thing at some point.