The truth that a handful of people that flew into varied components of India from the UK have examined constructive for the coronavirus is trigger for alarm just because these infections had been found the moment India tightened its screening course of for inbound fliers. It’s very doubtless that for the previous seven months, ever since India restarted flights to and from different nations by means of so-called journey bubbles, there was a gentle trickle of contaminated folks into (and likewise out of) the nation. The screening course of was tightened following panic over the brand new pressure of the Sars-CoV-2 virus recognized within the UK (way back to September, though it is just in latest weeks that it has hit the headlines after changing into the dominant pressure within the nation, and inflicting a surge in infections). UK officers have stated the brand new pressure is 70% extra contagious (or infective) than the outdated one. They additionally say that in lots of components of the nation, it has turn out to be the dominant pressure. That would imply a minimum of among the folks recognized as Covid-positive in Monday’s screening at airports might probably be carrying the brand new pressure.
Indian well being officers insisted at a briefing on Tuesday that the brand new pressure hasn’t been noticed in India, however that is a kind of statements that’s economical with the reality. The actuality is that India doesn’t sequence sufficient viral genomes for this to be stated with any quantity of certainty, however in all of the briefings (and it’s normally by the identical worthies who’re accountable for India’s Covid response) I’ve listened in on, I’ve by no means heard the phrases “we don’t know” or “we can’t say for sure” ever getting used. Indeed, what they lack in data, these folks normally make up for with certitude. The appropriate reply, as an example, to a question on whether or not the brand new pressure is in India can be: it hasn’t been recognized in our checks, however we don’t sequence sufficient viral genomes to say for certain; we are actually rising the quantity of genomes we sequence. That wasn’t so tough, now, was it? As I wrote in Tuesday’s column (Dispatch 230), provided that the brand new pressure has been round since September, and flights have been working between varied airports within the two nations, there’s each probability that the pressure might already be in India – however we have no idea for certain.
In Tuesday’s column, I wrote about how the UK had caught a fortunate break – one of many generally used RT-PCR checks confirmed solely items of two genes within the end result, as in comparison with the three it normally does. One of the brand new pressure’s 17 recognized mutations was answerable for this. The Reverse Transcription Polymerase Chain Reaction or RT-PCR check is taken into account the gold commonplace in terms of diagnostic checks for Covid. It identifies the viral RNA (ribonucleic acid, the genetic materials) by changing it into complementary DNA, which it does utilizing an enzyme referred to as reverse transcriptase. Then a sequence of chemical reactions are used to amplify the complementary DNA sections. The quantum of viral DNA is then measured utilizing fluorescent markers. The check in query within the UK was calibrated to test for 3 totally different RNA targets – and due to the mutation, it discovered solely two. Ergo, the nation didn’t actually need to preserve sequencing viral genomes to determine whether or not the an infection was brought on by the brand new pressure – if a check confirmed solely items of two genes within the end result, it indicated the virus was the brand new pressure.
Apart from aggressively sequencing extra viral genomes, India would do nicely to gather extra data – as an example, each RT-PCR check additionally measures viral masses – from the molecular checks it conducts (the fast antigen checks, aside from being unreliable, aren’t of a lot use on this context) somewhat than merely treating the output as a binary sure/no. Indeed, had a system to do that been in place, well being officers right here may need been in a greater place to reply the unique query: is the brand new pressure in India?