‘All adults in Spain should start to receive a booster shot’

Miguel Hernán, a professor of epidemiology at Harvard University, talks to EL PAÍS about the spike in coronavirus cases, the need for greater restrictions and whether omicron will overtake delta

Miguel Hernán, a professor of epidemiology at Harvard University.
Miguel Hernán, a professor of epidemiology at Harvard University.

Miguel Hernán is a professor of epidemiology at Harvard University. Over the past year, the Madrid-born researcher and his team have been analyzing the effectiveness and safety of Covid-19 vaccines in the United States and Israel, a study in which Oxford University in the United Kingdom was also involved.

Question. What is your valuation of the pandemic situation in Spain?

Answer. On the one hand, it’s a bit of a perfect storm. There was a rise in incidence caused by the delta variant due to the loss of protection from the vaccines, which is something that in the United Kingdom and Israel we have seen starts to happen five to six months after the second dose. Added to this is the emergence of a more contagious variant, omicron. The result is an extremely fast rise in contagions, not seen since March 2020. But on the other hand, we are in a much better place than a year ago. Everyone who is vaccinated is at lower risk of hospitalization. The key question now is to what degree will this rise in cases translate to more hospitalizations.

Q. It appears that the omicron variant is very quickly overtaking delta, which is currently the dominant strain in Spain.

A. It’s most likely that it will end up eliminating delta just as delta did with alpha, although the two could live side by side for a long time if delta is more effective at infecting the unvaccinated and omicron the vaccinated.

Q. Some data indicate that the omicron variant, despite being more contagious, causes less severe symptoms.

A. It’s true that in places where omicron is already dominant, such as areas of the United Kingdom and Madrid, we have not so far seen hospital admissions rise to worrying levels. But it is too soon to reach conclusions, we only discovered it at the end of November and in South Africa we have seen that it causes hospitalizations. It’s a scenario with great uncertainty because unless omicron is much less severe than delta, and no one is saying that, it’s likely that contagions will spiral and that this will translate to more serious cases.

Q. Would this also happen in countries with high vaccination coverage such as Spain?

A. We are seeing that the incidence is rising, even though there is high vaccination coverage. We have shown that the risk of hospitalization drops significantly among the population that has received two doses, but also that this protection drops five or six months after a person is fully vaccinated. This must make us cautious. Spain is in a situation in which all adults should start to receive a third dose.

Q. All adults?

A. Yes. There are countries that began to do this earlier, such as the United Kingdom, which has also reduced the waiting period between the second and third dose from six months to three. What we have seen in our studies is that the third dose lowers the risk of hospitalization in all age groups and also transmission. Spain’s vaccination campaign has been exemplary, but perhaps the country has lowered its guard with third doses. Without them, the risk of infection is high, and even though the risk of hospitalization is low, it also rises. In a situation where there are lots of contagions, this increases the pressure on the healthcare system. The vaccination centers that we saw at the beginning of the campaign have not been set up for third doses and I think that is something that must be strengthened now. We are a little late.

Q. Are we once again heading towards tight restrictions, such as the ones adopted by the Netherlands, which has imposed a nationwide lockdown?

A. To a certain point, restrictions on movement are inevitable. The Netherlands has decided on them and the United Kingdom is considering doing so for two weeks so that the incidence falls. These governments are being cautious and want to lower infections before the healthcare system becomes overwhelmed. There are two basic tools, which are ones that we already know: face masks and reducing [social] contact. Adding to this now are third doses.

Q. In some cases, however, it seems like authorities are waiting until after Christmas to make decisions.

A. It’s logical that there is resistance. No one wants to have another Christmas like the one in 2020. But it’s obvious that the sooner these measures are taken, the sooner the exponential transmission – which could overwhelm healthcare systems – can be curbed. We also have to take into account that, if they are applied earlier, they will be needed for a shorter time.

Q. In Spain, there are regions such as Madrid, that have applied fewer restrictions than others.

A. Yes. This is partly explained by the fact that healthcare staff have not complained. In London, [UK Prime Minister] Boris Johnson, was forced to adopt stronger measures when hospital workers took to the street. In Spain this hasn’t happened, even though there have been many moments in which there was chronic pressure on the system. In other places, it would be inconceivable for measures not to be taken when intensive care units are at 100% of pre-pandemic capacity for sustained periods – a point which exceeded 150% in several moments.

Q. In the last few days, we have seen primary healthcare systems become overwhelmed, while the low capacity of contact trackers has become evident. Are we repeating the same mistakes?

A. There are things that are much better and others that could have been improved more. Epidemiological monitoring today has more and better data than a year ago. There has been a good vaccination drive. But there is still work to be done. That’s where a Spanish public health agency that is scientifically strong and has the autonomy to evaluate the situation and propose decisions, is needed.

Q. In the past few days, pharmacies in Spain have sold out of antigen home testing kits. Is this a serious problem?

A. These tests could be a very useful tool if they were very cheap and the population could use them three times a week, for example. This would allow us to know if we are infected when we are asymptomatic and can spread the virus, which is one of the keys to the difficulty of stopping the pandemic. Using them occasionally, as is done now, is obviously better than nothing, but its impact is limited.

Q. What do you think about the vaccination of children between the ages of five and 11?

A. It’s another tool to contain transmission. Vaccinating this age group is safe. However, in the case that not everything could be done at once, third doses for all adults should be prioritized.

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