NACI published new advice, as of last week, on the topic of mixing vaccine schedules. NACI has now recommended that either AstraZeneca COVID-19 vaccine or an mRNA COVID-19 vaccine product may be offered for the subsequent dose in a vaccine series started with AstraZeneca. Either may be offered.
The evidence that was used by the committee to issue that recommendation included both safety evidence and evidence on the immune response. There were several studies at the time, one from the United Kingdom, one from Germany and one from Spain. All of them reported a good safety profile when vaccines were mixed between AstraZeneca and mRNA vaccines. There was also one study on the immune response from Spain. I'll note that a number of studies came out preprinted last week as well, two from Germany, on the topic of immune responses when vaccines are mixed.
The committee has made that recommendation based on the risk of VITT, or thrombosis with thrombocytopenia, after first and second doses of AstraZeneca. They also considered the possibility of increased short-term reactogenicity with a mixed schedule and emerging data on the immune response from that mixed schedule that I mentioned. That was all—