Posts filed under General (3148)

Team Ratings for Round 12

More weird stuff this week. A game that was previously listed as Round 12 is now listed as Round 14. Also because the game scheduled for last week was not played, my last week results refer to the previous week for which I have already published the result.

The basic method is described on my Department home page.
Here are the team ratings prior to this week’s games, along with the ratings at the start of the season.

Performance So Far

So far there have been 65 matches played, 44 of which were correctly predicted, a success rate of 67.7%.
Here are the predictions for last week’s games.

Predictions for Round 12

Here are the predictions for Round 12. The prediction is my estimated expected points difference with a positive margin being a win to the home team, and a negative margin a win to the away team.

The current NZ Covid restrictions happened because someone at risk of infection in their job developed symptoms consistent with Covid and got tested.   With the first load of Pfizer vaccines arriving today, that raises a question about testing.

All the current vaccines seem to do best at preventing serious illness and death, and slightly less well at preventing mild illness. We don’t have really good data on preventing asymptomatic illness, but the information we have suggests that the trend continues and they’re somewhat less effective at preventing asymptomatic illness.  For most purposes that’s a great tradeoff — Covid is a global catastrophe only because people get sick and die, that’s how it’s different from the common colds caused by other coronaviruses.  For preventing border incursions things are more complicated.

When we vaccinate the first target group — people working at the border, the highest-risk healthcare workers, and their household contacts — we dramatically reduce the chance they will get sick or die from Covid, and we reduce, less dramatically, the chance they will get infected and pass the virus on.  We should expect fewer cases of the virus getting past the regular workplace testing — but when it does, it’s less likely to be stopped by someone stepping up and getting a test on their own.  Outbreaks are likely to be bigger by the time we see them, with a higher risk of needing lockdowns.

This doesn’t mean we shouldn’t vaccinate border workers. The whole point of the vaccine is to stop people getting sick and dying, and that’s how we should use it. The answer isn’t to use MIQ workers as coal-mine canaries. We do need to think about how to change testing to respond to the new circumstances.  Many experts have already been calling for more frequent testing of high-risk workers, ideally using new saliva-based tests to reduce the ouch factor.  The case for more-frequent tests will be much stronger as we progressively vaccinate the people at highest risk and become less likely to pick up outbreaks by waiting for people to get sick. 

Team Ratings for Round 16

The basic method is described on my Department home page.
Here are the team ratings prior to this week’s games, along with the ratings at the start of the season.

Performance So Far

So far there have been 109 matches played, 70 of which were correctly predicted, a success rate of 64.2%.
Here are the predictions for last week’s games.

Predictions for Round 16

Here are the predictions for Round 16. The prediction is my estimated expected points difference with a positive margin being a win to the home team, and a negative margin a win to the away team.

Team Ratings for Round 9

The basic method is described on my Department home page.
Here are the team ratings prior to this week’s games, along with the ratings at the start of the season.

Performance So Far

So far there have been 43 matches played, 24 of which were correctly predicted, a success rate of 55.8%.
Here are the predictions for last week’s games.

Predictions for Round 9

Here are the predictions for Round 9. The prediction is my estimated expected points difference with a positive margin being a win to the home team, and a negative margin a win to the away team.

Team Ratings for Postponed Matches

The basic method is described on my Department home page.
Here are the team ratings prior to this week’s games, along with the ratings at the start of the season.

Performance So Far

So far there have been 64 matches played, 44 of which were correctly predicted, a success rate of 68.8%.
Here are the predictions for last week’s games.

Predictions for Postponed Matches

Here are the predictions for Postponed Matches. The prediction is my estimated expected points difference with a positive margin being a win to the home team, and a negative margin a win to the away team.

First, two new vaccines.  Johnson & Johnson and Novavax put out press releases about their vaccines last week. These are two vaccines that NZ has agreements to buy.  The Novavax vaccine is (a slightly modified version of) the viral spike protein. The mRNA vaccines (Moderna, Pfizer) get your body to make this protein, and the DNA vaccines (AstraZeneca, J&J) get your body to make mRNA to make the protein; a protein vaccine cuts out the middleman.   Novavax are reporting good results, estimating 95% efficacy against the original variants of SARS-2-CoV [?Covid Classic], about 85% against the B 1.1.7 (“UK” variant) and about 60% against the B 1.351 (“South Africa” variant). That’s as good as the mRNA vaccines against the original strains. It might well be as good against the new variants — we don’t have direct randomised trial estimates of effectiveness for the new variants and the mRNA vaccines, but we have antibody tests that suggest substantial but lower protection. Johnson & Johnson didn’t provide much data, and they aren’t claiming as high effectiveness, but they are claiming to prevent serious disease and death, and it’s a single-shot vaccine. We will presumably see more information from both companies when they are evaluated by the FDA and its European counterpart, as we did for earlier vaccines.

Next, the AstraZeneca vaccine in people over 65.  The situation has clarified a bit, though it’s still not clear what number Handelsblatt were quoting.  There is very little Covid data (so far) on people over 65, because there were very few in the trial.  This will improve somewhat when data are released from trials in India and the US.  There is good reason to expect that the vaccine would work in people over 65, but very little direct experience.  In a usual drug-approval situation there is a very strong status-quo bias: the status quo is often not that terrible; the drug doesn’t realistically promise a big improvement; you don’t want to give drug companies incentives to cut corners in trials. Usually it’s better to postpone a decision for a year or so to get better information. With Covid, the status quo is a massive human and economic disaster, and the balance of risks is very different. Leaving people unvaccinated is dangerous, epidemiologically and to the global economy as well as to them personally, so it’s not clear whether the ‘safe’ approach for regulators is to approve the vaccine for all ages or carve out an over-65 exception. It probably depends on the country.

Finally, arithmetic. Israel has been doing well at delivering vaccines, and we’re starting to see rates of infection after vaccination. These aren’t straightforwardly comparable with vaccine efficacy numbers.  A story in the Jerusalem Post has the headline Just 0.04% of Israelis caught COVID-19 after two shots of Pfizer vaccine  and goes on to say (emphasis added)

According to the studies conducted by Pfizer, the vaccine had an efficacy of about 95%, which is considered very high. The Israeli data appear to confirm the inoculation’s effectiveness, showing an even more promising result.Later in the day, Maccabi Healthcare Services – one of the country’s four health maintenance organizations – released the first results of the vaccination campaign of its members, with the organization also comparing the data to a control group that did not get inoculated.
Some 248,000 Maccabi members were already a week after the second shot as of Thursday. Of those, just 66 got infected with the virus, the majority of them over the age of 55 and about half of them with preexisting conditions. All those infected experienced only a mild form of the disease, and none were hospitalized.Over the same period of time, some 8,250 new cases of COVID-19 emerged in the control group of some 900,000 people having a diverse health profile. Those who were not inoculated were therefore 11 times more likely to get the disease than those who were immunized, showing 92% effectiveness.

95% effectiveness means you’d expect 5% of vaccinated people to test positive as infected if 100% of unvaccinated people did. Or 0.05% test positive as infected if 1% of unvaccinated people did. But 1% is a very high rate — the US, at its very worst, wasn’t getting close to 1% of the population as new cases in a week.

Team Ratings for Postponed Games

The basic method is described on my Department home page.
Here are the team ratings prior to this week’s games, along with the ratings at the start of the season.

Performance So Far

So far there have been 105 matches played, 67 of which were correctly predicted, a success rate of 63.8%.
Here are the predictions for last week’s games.

Predictions for Postponed Games

Here are the predictions for Postponed Games. The prediction is my estimated expected points difference with a positive margin being a win to the home team, and a negative margin a win to the away team.

Team Ratings for Round 8

The basic method is described on my Department home page.
Here are the team ratings prior to this week’s games, along with the ratings at the start of the season.

Performance So Far

So far there have been 37 matches played, 21 of which were correctly predicted, a success rate of 56.8%.
Here are the predictions for last week’s games.

Predictions for Round 8

Here are the predictions for Round 8. The prediction is my estimated expected points difference with a positive margin being a win to the home team, and a negative margin a win to the away team.

Team Ratings for Postponed Matches

The basic method is described on my Department home page.
Here are the team ratings prior to this week’s games, along with the ratings at the start of the season.

Performance So Far

So far there have been 63 matches played, 43 of which were correctly predicted, a success rate of 68.3%.
Here are the predictions for last week’s games.

Predictions for Postponed Matches

Here are the predictions for Postponed Matches. The prediction is my estimated expected points difference with a positive margin being a win to the home team, and a negative margin a win to the away team.

There was a mysterious piece of vaccine news yesterday when German paper Handelsblatt claimed that the Oxford/AstraZeneca vaccine wasn’t going to be approved in Europe for people over 65 because it had only 8% efficacy in that group.  From the start, he claim of 8% efficacy was clearly either misquoted or misleadingly calculated, but it caused quite a bit of angst — and it is quite possible that the vaccine won’t be approved for older people

The problem is that the vaccine basically wasn’t tested in older people.  In contrast to the Moderna and Pfizer trials, the Oxford/AstraZeneca trials mostly recruited people under 55. The set of four trials reported in December had 428 people over 70, and fewer than 600 between 55 and 70.  Exactly none of these people had the low-dose first injection where the vaccine looked more effective. There’s more data from additional trials, eg in India, but still not very many older people recruited. In fact, about 8%^* of all the trial participants were over 65.

Testing in older people is valuable because they’re the single most important group to vaccinate, and because the immune system changes with age.  It’s always possible that a vaccine will be less effective in older people, because they won’t generate as good an antibody response. In normal circumstances, a vaccine with trial data like this would probably be approved with some upper age limit — partly because of real uncertainty and partly because you want to discourage manufacturers from doing trials that don’t include the most important target populations.

Right now, though, we’re seriously short of vaccines. The trials confirm the Oxford/AstraZeneca vaccine does produce good concentrations of antibodies in older people, so there’s reason to expect it will prevent disease. As an additional encouragement, the two mRNA vaccines didn’t show any signs of being importantly less effective with age.  Soon there should be data from a Johnson & Johnson vaccine using the same basic technology as the Oxford vaccine, and it will be even more reassuring if that is effective in older people.  All in all, it wouldn’t be unreasonable to use the Oxford vaccine at least in the short term, but it’s not really surprising that there’s a controversy.

It is more surprising that Handelsblatt would get the facts so badly wrong.

Update:  An actual table with actual data has escaped on to the internet, saying that the point estimate for efficacy in 65+ year olds is 6.3%, with a confidence interval from -1400% to 94%. That is, the vaccine could make you 14 times more likely or 19 times less likely to get Covid, or anything in between. That still doesn’t really explain where the 8% number came from, but it does show the basic problem that there just isn’t direct information on efficacy in older people.  You have to either rely on the antibody levels, or not. 

^* No, that apparently isn’t just a coincidence