Alex Nowbar’s journal reviews—3 April 2020

Alex Nowbar reviews the latest research from the top medical journals.

Uninformed on both sides of the pond

Covid-19 is the biggest deal since, well, ever. But how clued up are we? Geldsetzer reports the findings of an online survey of 3000 members of the public in the US and 3000 in the UK. Knowledge of the generally accepted case fatality rate was reasonable, as was knowledge of symptoms and mode of transmission and prevention. Well done respondents! Where it gets hairy, though, are the answers regarding intent to discriminate against individuals of East Asian ethnicity. Over a quarter of respondents answered yes to the following “Do you think it would be prudent for you to not eat at Chinese restaurants for the next few weeks to reduce the risk of getting infected with the new coronavirus?” Sigh. Still, not as bad as when Trump says things like, “You can call it a flu.” No, you really can’t.

Ann Intern Med doi:10.7326/M20-0912

Covid in care homes

We want covid-19 to stay out of all homes, but especially care homes because the elderly are at high risk of death. A case was identified on 28 February 2020 at such a facility in Washington State, USA. There followed a rigorous intervention by the Centers for Disease Control and Prevention (CDC), with an investigation, contact tracing, quarantine, isolation, enhanced infection control measures, the works. By 18 March, 101 residents, 50 staff, and 16 visitors had confirmed covid-19 across 30 facilities in the region (staff and residents transferred between facilities). What does this report tell us that we didn’t already know? Of the 101 diagnosed residents, 55 were admitted to hospital and 34 died. One visitor died, but none of the staff had died. Care home residents are very vulnerable. This isn’t really news. But there are some lessons: these data support screening of healthcare staff and visitor restriction to mitigate the calamitous spread. Infection control strategies and staff practices (such as isolation when symptomatic) need to be particularly stringent in care homes.

N Engl J Med doi:10.1056/NEJMoa2005412

 Masks unmasked

Do you know your surgical mask from your N95? Or your FFP2 from your EHMR? Or your FFP3 from your C-3PO? Okay, that last one is a Star Wars character. But, other than C-3PO, which is the odd one out? It’s the EHMR (elastomeric half-mask respirator) because it’s reusable whereas the other masks are disposable. The threat of PPE shortage makes this a reusable option of interest. Pompeii et al happened to carry out an emergency outbreak simulation in 2019 in which they compared fit testing and training between the N95 and EHMR. They randomised almost 200 staff to one of the two masks. They demonstrated that staff were able to be rapidly fit tested and trained to use the EHMR compared to the standard N95. This study was not testing the efficacy of the mask for reducing transmission of covid-19 (prior data show it provides the same level of respiratory protection as an N95). But it would be worth some expert consideration to see if EHMRs are a viable alternative in a state of PPE shortage.

Just for fun, did you know that FFP simply stands for Filtering Facepiece? Disappointingly non-technical isn’t it. And that an N95 is one of 9 FFP types in the US classification system, with the “95” meaning that at least 95% of very small test particles were blocked. And “N” means Not resistant to oil. In the European classification system, there are FFP1, FFP2 and FFP3 with the higher number meaning greater filtering (in the NHS we use FFP3). An N95 is roughly equivalent to an FFP2. There you have it, clear as mud.

JAMA doi:10.1001/jama.2020.4806

Covid-19 in newborns

If you are pregnant right now, you probably have quite a lot to worry about. Will there be enough healthy staff to take care of you and your newborn? But, importantly, if you get covid-19, will your newborn get it? And I would suggest you don’t expect the answers any time soon. In China, they have closely studied samples from a very small number of babies with covid-19 positive mothers and found the murky waters only murkier. Initial study (January 2020) showed no evidence of the virus in nine newborns. Testing was with PCR, which looks for SARS-CoV-2 nucleic acid. Now (March 2020) there are antibody tests.

Dong and colleague present data on one newborn whose mother developed symptoms a month before delivery, was hospitalised, and who tested positive by PCR at that time. PCR on the mother’s vaginal secretions at birth and on the newborn’s nasopharyngeal swabs (and later the mother’s breast milk) were negative. However, SARS-CoV-2 IgG and IgM were present in the newborn at 2 hours of age, along with a raised white cell count, IL-6, LDH, ALT, and CK, but normal CRP.

Zeng and colleagues examined six newborns from mothers who had had mild symptoms. All six had negative PCR test results, but two had raised SARS-CoV-2 IgG and IgM. It is very difficult to interpret these findings with no other newborn data to reference or a “gold standard” for defining an infection in a newborn. However, the presence of IgM suggests in utero (rather than postnatal) transmission because IgM antibodies take days to appear and do not cross the placenta. Could these antibody results be false positives though?

JAMA doi:10.1001/jama.2020.4621

JAMA doi:10.1001/jama.2020.4861

Desperate days

We do not know what substance, if any, people who have recovered from covid-19 hold in their plasma that might be of use to those with the condition. We also did not know when we used convalescent blood to treat Ebola in 2014, nor MERS in 2015. But a few years before that, for H1N1 influenza a randomised controlled trial hinted that IV immunoglobulin was effective. Challenging though it may be, we need a randomised controlled trial of such a therapy for COVID-19 now. Shen et al gave it a go, presumably out of desperation. Their case series describes the 5 patients (3 men and 2 women) they treated in Shenzhen, China. These patients were on mechanical ventilation and had already had antivirals and methylprednisolone before the plasma infusion. Donor plasma had a high titre of relevant virus antibodies and donors had been asymptomatic for at least 10 days. 3 patients were discharged home but 2 remain on mechanical ventilation. There was no control group and the sample size very small so academically there is very little we can conclude from this. We need to deliver much better evidence and fast.

Alex Nowbar is a clinical research fellow at Imperial College London

Competing interests: None declared