#15,698
Although the actual number of confirmed COVID reinfections remains reassuringly small, identifying such cases requires more than a little bit of luck since so many people who are infected are never tested, and fewer still have genomic sequencing data available for both illnesses.
Three days ago, in PrePrint: Genomic Evidence of a Sars-Cov-2 Reinfection Case With E484K Spike Mutation in Brazil, we looked at one such case recently reported from South America, while in the past we've looked at other cases in India, Hong Kong, the Netherlands & Belgium, and in Nevada.
There remain conflicting studies on how long post-infection immunity lasts, with one recent study (see Immunological memory to SARS-CoV-2 assessed for up to 8 months after infection) finding that most of a study group (n=188) still had evidence of immunity more than 6 months after recovery.
But there were wide differences (up to 100-fold) in immune responses between individuals in this study group, and so some people may be susceptible to reinfection much sooner than others. And exactly how emerging COVID variants will respond to these post-infection immune responses remains unknown.
With the caveat that there are a lot of (both known, and unknown) moving parts here, and one, two, or even a dozen individual reports - while interesting - don't necessarily constitute a major a trend, we've another PrePrint study (not yet peer reviewed) on a confirmed reinfection - this time with the B.1.1.7 (aka VOC -202012/01 or `UK;) variant virus.
The subject was a 78 y.o. male with a variety of comorbidities including: Type 2 Diabetes, diabetic nephropathy on haemodialysis, COPD, sleep apnoea, and ischaemic heart disease (but no history of immunosuppression) who first fell ill with (mild) COVID in April.
Follow up exams and blood tests showed he maintained SARS-CoV-2 antibodies as recently as mid-November, but in mid-December he showed up at the A&E following 3 days of shortness of breath, which had worsened overnight, leaving him severely hypoxic and unable to talk.
The subject was intubated, and diagnosed with `. . . . severe Covid-19 pneumonia complicated by mycocardial infarction with resulting trifascicular block and Atrio-Ventricular (AV) dissociation and pulmonary oedema'.
The new viral infection was sequenced and compared to the one in April. The authors describe their findings:
The WGS results confirm reinfection with a different lineage 8 months after initial infection in the absence of significant immunocompromise. The reinfection was with the ‘new variant’ VOC202012/01. This variant has been recently identified in the UK, and is rapidly spreading, especially in London and the South East of England and South Wales and may be responsible for a surge in new cases here1.
The ‘new variant’ is characterised by numerous mutations in the spike region which causes diagnostic escape in PCR assays using the ‘S’ gene as a target for amplification1,2. The numerous spike region mutations also raise questions about possible immune escape and/or vaccine evasion and likelihood of reinfection.
The full preprint can be accessed at the link below. I've only excepted a small passage from the conclusions.
Confirmed Reinfection with SARS-CoV-2 Variant VOC-202012/01
David Harrington, Beatrix Kele, Spiro Pereira, Xose Couto-Parada, Anna Riddell, Suzanne Forbes, Hamish Dobbie, Teresa Cutino-Moguel
Barts Health NHS Trust London, UNITED KINGDOM
(EXCERPT)
The development of reinfection in this case may just reflect waning immunity after 8 months since primary infection in a high-risk individual with multiple comorbidities. Anti-SARS-CoV-2 antibodies were still present shortly before onset of reinfection, with no evidence of antibody waning. This may raise some concerns about immune evasion by this new variant, which is a concern with the high number of spike region mutations seen.
We have no assay for SARS-CoV-2 antibodies recognising spike antigen, and neutralising antibody studies are pending. The antibodies detected recognise ‘N’ antigen, so drawing conclusions is difficult. The group of mutations identified in VOC-202012/01 appears to have significantly increased transmissibility compared to previously described mutations or haplotypes, but there is as yet no evidence of increased pathogenicity associated with these mutations1.
In this case the initial illness was mild, and the reinfection with the new variant was critical/life-threatening. More severe illness on the second episode has been reported before in confirmed reinfections not caused by VOC-202012/01,4. Rapid work on learning about immune, vaccine and diagnostic escape is needed, as are data on severity of illness caused by VOC-202012/01/
For now, we seem to be stuck in that all-too-familiar infectious disease territory; somewhere between not enough cases to be alarming, but too many cases to ignore.
Stay tuned.
