Archive for vaccination

SARS-Cov-2 Vaccine strategy: One Jab or Two?

Posted in Covid-19 with tags , , , , , on January 13, 2021 by telescoper

I’ve been thinking quite a lot about the issue of the Coronavirus vaccination programmes currently underway and have had some interesting and informative exchanges on Twitter about it. This morning’s news that AstraZeneca has finally applied to the European Commission for permission to market its vaccine within the European Union reminded me of those discussions so I thought I’d post a question here. I genuinely don’t know the answer, incidentally, so there’s no agenda here!

As you probably know all SARS-COV-2 vaccines (Moderna, Pfizer/Biontech and AstraZeneca) require two doses, administered about three weeks apart, for maximum efficacy. It’s worth saying before going on that the scientists involved deserve high praise for developing these highly effective vaccines at a speed that has exceeded all expectations.

At the moment however supplies of these vaccines are fairly limited and it’s early days for immunization programmes so there are serious logistical problems to be solved before we get anywhere near full vaccination. I grabbed this from Twitter yesterday showing the state of play in various countries:

Note, incidentally, that Denmark is doing particularly well within the EU but France, Netherlands, Luxembourg and Belgium have started very slowly. Ireland is about mid-table.

At the top of the league is Israel, though  they are not offering vaccination to the Palestinian people whose lands they occupy. Israel has just reported that after 12 days the Pfizer/BioNTech vaccine has about 50% efficacy after one dose based on results from its own programme. That number is roughly consistent with initial estimates of from trials this vaccine but the statistics aren’t great and there is a considerable margin of error on these figures.

Now the question I am asking myself is that given the limited supply is it better at this stage to give as many people as possible one dose of the vaccine, or follow the manufacturers’ original plan and give two doses to half as many people? There are reports that the UK has been deferring the second dose beyond the recommended interval, where there is no data on its efficacy. Perhaps I’m being excessively cynical but it seems to me that the UK Government’s approach is more driven by public relations than by public health considerations.

I understand that there are difficult issues here, not least the ethical one of having people sign up for a specific two-dose vaccination only to find that’s not what they get. Another issue is the speed with which doses are being made available relative to the size of the population. Yet another issue is who you prioritize.

Above all, though, there is the question of what you mean by “better”. One criterion would be to save as many lives as possible. Another might be to slow the rate of infections as much as possible. Another might be to allow the economy to open up as early as possible. These are all different and would lead to different decisions, particularly with regard to who should get the vaccine. Saving lives obviously means protecting the vulnerable and the people who care for them (e.g. health workers). Economic considerations would however lead you to prioritize those on whom the economy depends most directly, which would include workers who can’t easily work from home (many of whom are in low-paid manual jobs).

The following poll is therefore going to be very unscientific, but I’m interested to find out what people think. In  order to keep it simple, lets suppose you have a batch of two million doses of a vaccine (say the Pfizer one) and the next batch is due in three months.

You have to decide between the following two options:

  1.  Give 1,000,000 people one dose now and another dose in three weeks’ time
  2.  Give 2,000,000 people one dose now and hope that it is effective for three months (or that additional supplies appear more quickly than anticipated).

Vote now!

A similar poll I did on Twitter a while ago can be found here: there are some quite interesting comments in the ensuing thread.

Comments are of course welcome through the Comments Box!

P.S. I’m quite low down the pecking order in Ireland so it’s unlikely I’ll get vaccinated before the summer.

Vaccination in Ireland

Posted in Covid-19 with tags , , , , , , , on December 5, 2020 by telescoper

A very interesting twitter thread from Dr Ronan Glynn (Ireland’s Deputy Chief Medical Officer) inspired me to write something in response to the very positive recent developments with regard to a SARS-CoV2 (Covid-19 vaccine). In Switzerland the regulator does not feel that there is enough data yet for approval to be granted yet, so I have some reservations about the fast-tracking of the process in the United Kingdom. Nevertheless there has to be a tradeoff between the risk of potential reactions or side-effects of a vaccination and the immediate danger to public health arising from Covid-19. As someone recently said to me on Twitter: “if you’re not going to fast-track during a global pandemic, when would you?”.

Here in Ireland it is likely that a vaccination programme will commence early in the New Year. To answer a question I posed a few weeks ago, priority will be given to front-line health care workers, especially those working in care homes, and the elderly. If all goes to plan there will be something like full vaccination of the population by September 2021.

I am not in a priority group so will have to wait a while for my jabs, but I will certainly take the vaccine as soon as it is available to me.

No doubt there are some people out there who for various reasons will refuse to be vaccinated. I doubt anything I say here will persuade them but it is I think valuable to look at the history of vaccination programmes in Ireland for various illnesses, which is what Dr Glynn’s thread does.

To give a few examples:

  • Smallpox. In 1863 vaccination against smallpox was made compulsory for all children born in Ireland. Deaths fell from 7,550 for the decade to 1880 to the last reported death from smallpox here in 1907. Smallpox was declared eradicated in 1979 – this one vaccine saved 100s of millions of lives globally.
  • Diptheria. Diphtheria was a very common cause of death among children until the 1940s – there were 318 deaths from it reported in Ireland  1938. With the introduction of a vaccine, the number of deaths fell year on year with 5 deaths in 1950; the last death notified from diphtheria was in 1967.
  • Poliomyelitis. In Ireland, polio infection (mainly affecting young children causing long term paralysis) became more common after 1920 with major epidemics during the 1940s & 1950s. A vaccine was introduced in 1957. The last reported case of polio here in Ireland 1984.
  • Measles. The number of cases of measles declined dramatically after introduction of measles vaccine in 1985, from 10,000 cases in 1985 to 201 cases in 1987.
  • Meningococcal Meningitis. In 1999, there were 536 cases of meningococcal meningitis in Ireland The meningitis C vaccine was introduced in 2000, with the meningitis B vaccine introduced in 2016. Cases of meningococcal meningitis have dropped more than 80% since these vaccines were introduced.

These are of course wonderful advances in public health, but none of them provided total relief immediately. It will be the same with Covid-19. The availability of a vaccine will not end the pandemic overnight, but at least it will enable us to plan for a phased return to normal.

 

While there is great cause for long-term optimism, there are still reasons to be anxious in the short term. There will be many months before a full vaccination programme is in place and in that time cases (and, sadly, deaths) could rise substantially. There is a real danger will think that it’s all over, that they can let down their guard and ignore social distancing.

Ireland is currently relaxing its Covid-19 restrictions for the Christmas period, but it is doing so from a level of over 260 new cases per day. The Coronavirus is currently circulating in the community at a far higher rate than it was in the summer and if it increases at a similar rate to August then we could be in for a huge surge. I fear that by the New Year we might be in real trouble again. It would be tragic if people lost their lives owing to complacency with safety so nearly in sight.

 

Covid Questions for Ireland

Posted in Covid-19, Maynooth with tags , , on November 15, 2020 by telescoper

I’ve just done my daily update of Covid-19 numbers here and thought I’d show the latest figure:

There are now 262 data points on these graphs. When I started doing the updates I thought it might carry on for two or three months -i t’s now been almost nine and there’s no end in sight.

As you can see the 7-day average of new cases has been falling steadily since entered the period of Level 5 restrictions that is now about half-way through. That, of course, is good news. The problem is that the rate of decrease is really quite slow. The number of new cases on each day for the last week (including today) were: 270, 270, 362, 395, 482, 456, and 378 (today). That is fairly flat, the steep downward trend of the previous week apparently faltering. As a rough guess I’d say that by the time we come out of the current period of restrictions (at the beginning of December) we’ll probably still be having over a hundred new cases per day.

I think that level is far too high for comfort, but the current government is probably going to find it difficult to resist the political pressure to exit the lockdown in time for Christmas. If that does happen, I can see another lockdown looming in January. My superiors at Maynooth University are talking about having on-campus teaching again next Semester, but I think that’s highly unlikely in the circumstances.

Things are even worse in Northern Ireland where the number of new cases announced today was 478. Daily cases have been running higher there than in the Republic for some time, despite the fact that the six counties of Northern Ireland have a population of just 1.9 million compared to the 4.9 million of the 26 counties  in the Republic.

That brings me to the issue of the Pfizer Covid-19 vaccine that everyone is getting excited about. Assuming that it passes the various tests needed for it to be approved, Ireland would get about 2 million doses from the stock procured by the European Union.  The population of Ireland is about 4.9 million, and each person would require two doses, which means that supply will only enable about 20% of the population to be vaccinated.

(Actually I don’t know whether the 2 million refers to people that can be vaccinated or individual doses, but even if it’s the former that still accounts for only 40% of the population.)

The question then is who should be prioritized? I think we’d all agree that all health care workers should be vaccinated ASAP but that’s only about 25,000 people (source). Who should get the other doses? Most people seem to be assuming that those at highest risk of mortality should be vaccinated, but there’s also a case to be argued that  it should it should be those groups within which the virus is most likely to spread that should get it, which is presumably the otherwise healthy population.

I don’t know the answer, but it will be interesting to see how this all develops. In any case as far as I can see it there’s very little prospect of high levels of population immunity being reached by this time next year. And that’s even if the vaccine is available soon, which is by no means clear will be the case. As a matter of fact I wouldn’t bet against me still having to do daily updates on Covid-19 statistics for most of next year.