I actually want to ask about the same thing—the interval between the first and second doses. Certainly, a lot of people are concerned about the interval. I have had health care people saying, “Look, we're high risk. Why are we getting only one dose?” I've also had concerned elderly people saying, “We're supposed to have the same dose after three or four weeks. Why is it longer?”
The evidence, certainly for AstraZeneca, seems to suggest that it's better if you have a longer interval between doses. With both Pfizer and Moderna, to my understanding, although I haven't looked in the last few days, the evidence was that starting at about three weeks, at least in young people, you had about 90% efficacy. The evidence from British Columbia, Quebec, Israel and the United Kingdom seems to be that for at least two months you have pretty good immunity. We have other vaccines where there are two doses and where it's six months in between. We have reason to believe that immunity is going to last for the full four months.
For someone like me, that's no problem. As somebody who still works a bit in health care, I've had my first dose. I'm not going to have my next dose for four months. The concern is more with the elderly, because studies seem to at least suggest that their immune response is poorer. The initial data from Israel suggested that one shot wasn't protective, although that seems to have been reanalyzed in that, well, a lot of those people were getting infected in the first two weeks, when no vaccine was going to work.
I want to ask the person from NACI what the current evidence is regarding the safety of that increased interval in elderly people and people who might otherwise be immunosuppressed, such as people on chemotherapy.
Thank you.