Head of microbiology at the Vall d'Hebron Hospital

Tomàs Pumarola: "8% of covid cases detected in Barcelona are of the British variant"

Lara Bonilla
6 min
Tomàs Pumerola none of microbiology of the Hospital Vall de Hebron

BarcelonaThe new variants of the coronavirus have put health authorities on alert. There are many questions raised by the new variants and few certainties. In Catalonia, a sequencing effort is being made to identify cases of the British variant of the coronavirus, and it is a matter of days before the South African variant is also found. We spoke with the head of the microbiology service of the Vall d'Hebron Hospital, where they already detect between 6% and 8% of cases of the new variant.

A month ago you said in an interview in the ARA that we still did not have enough information to say that the British and South African variants were more pathogenic. Is this still the case?

At the moment, not yet. What we do know is that they are more transmissible. They are not more virulent, but the more they are transmitted, the more cases there are, as well as more hospitalisations and more mortality.

Should we be afraid of the new variants?

— We don't have to be afraid of them, but we do have to be tense and have respect for them. What we have to do is a careful careful monitoring of all the variants to see how they are evolving and what they represent for us biologically. Fear stops you and respect makes you work in a very active way, and this is what we are doing.

Is the surveillance of new mutations of the virus working in Catalonia and Spain?

Yes, a consortium of four hospitals has been created, with the Vall d'Hebron, Bellvitge, Germans Trias and Clínic - to sequence samples. We have been sequencing since the first week of the pandemic, but now we have increased our efforts because it is a complex technique that takes days and requires experienced personnel. What we do is to see the complete genome of the virus to know how it varies with respect to other variants circulating, if it can escape certain antiviral drugs, vaccines, if they can be more pathogenic or if they are better transmitted, and this must always be done hand in hand with clinical cases. The British variant was detected in the United Kingdom on 18 September, but the alert was not issued until 20 December. Why? Because it is one thing to detect it and another to know its biological behaviour. They detect it but they don't know what it is doing and in December they realise that it is predominant and that it is causing significant outbreaks and they issue an alert. And they know this because they have previously done sequencing work to learn more about the virus and how it evolves. And this allows them to take public health and vaccine formulation measures.

Pfizer and Moderna have said that their vaccines protect against the British variant and the American pharmaceutical company is already adapting its vaccine to the South African variant. Will the vaccines protect us from all variants?

— They don't have to, we don't know. We will know this as we see it. We have to combine surveillance of clinical cases with surveillance of the virus. Now an important target is to characterize all these cases of covid-19 in people who are perfectly vaccinated. If a person to whom I've given two doses of vaccine and who is fully protected, gets covid, I have to know if this virus is different from the one we have now.

So, if we have already been vaccinated, can we be re-infected with a new variant?

We don't know, we will have to see how it evolves and, as I said, surveillance is very important, because it allows us to make quick decisions. If we take the flu as a model, every year we have to get a flu vaccination and nobody is scared of that. The flu vaccine is 60% effective and maybe I get vaccinated and I still get the flu, but what we see very sporadically is that a person vaccinated against the flu is admitted to hospital because of complications from the disease. So, speculating with the flu as a model, perhaps we have a vaccine that does not protect 100% of a variant and the person may contract the virus but will hardly be admitted to hospital. One possible hypothesis is that the protection of the vaccine is much higher to prevent the severity of the disease than to prevent the disease itself. But it is not yet known. As I say, it is a hypothesis based on the flu model. Vaccines at the moment are relatively easy to modify and with the flu we do it every year. And if we have to modify the vaccine as the coronavirus evolves, nothing happens.

And if we've already been infected with coronavirus we can also be reinfected with the new variants.

— Yes, yes, we see several cases of reinfection with different variants of coronavirus, but all the reinfections that we see with new variants are mostly with mild or asymptomatic symptoms. And you would think, but we're getting into the realm of speculation here, that if we already have a certain level of antibodies we may have the disease but it's more difficult for it to be severe.

Will the British variant change the evolution of the pandemic?

— At the moment nobody has a crystal ball to predict the future. We have a system that generates quality data every day and this allows us to know in advance what may happen tomorrow and make decisions, but this is like the weather service, which gives predictions for three or four days but not for a month.

The feeling is that we are always behind the virus.

— We're behind, it's impossible to be ahead, because it's difficult to know how far we can go. What are we going to do? Lock everyone indoors for a month and destroy the economy for good? These are very difficult decisions and it is obvious that we will always be behind the virus, because it is impossible to be ahead because we don't know how it will evolve. In the end it's like a bicycle race. You can go with the peloton, or behind. And we are going with the peloton, very close to the virus, and not too far behind so that we can make decisions when things happen and not three months later.

But if the new variant is more transmissible and causes more cases and, therefore, more hospitalisations, will the health system be able to cope with it?

— You are assuming this in a scenario in which we do not take measures. If you put prevention measures in place, the virus will also find it harder to transmit, it will not be the same as if you don't. And what are the indicators that modulate the measures to be taken? Basically, hospital occupancy and ICU beds. The problem is when you have the need to stop other medical activities as a result of covid. That's when you have to increase the measures. But the measures are not taken taking into account the new variant, but according to the indicators of hospital occupancy.

Are you in favour of more drastic measures?

It will depend on the indicators and not so much on the virus. If we have a virus that is transmitted more, but that with the measures we have it is well controlled, more drastic measures will not be necessary, but if we worsen and the virus is not contained, we will have to put more drastic measures into place. We are in an extraordinarily dynamic process and the only thing we have to do is to generate reliable data so that the health authorities can take decisions.

Some seventy cases of the British variant have already been detected in Catalonia. I remember that at the beginning of the pandemic cases of covid were counted in dribs and drabs when the transmission was already communal. Could it be that the cases of the new variant are already many more?

— These 75 cases have been detected in the Vall d'Hebron, and in the Germans Trias we have detected one more. Wherever we look for it, we find it. Of all the cases of covid that we receive, which come from primary healthcare in Barcelona city and from Vall d'Hebron Hospital, the proportion is still low: 8% of covid cases are of the new variant. Now it is a minority, but it is logical to think that it will increase, according to the experience of other countries, and will end up being the predominant in the coming weeks. And we have only detected the English variant, but it would not be strange to detect in the coming days the South African variant, because it has already been detected in Europe, although in low proportion.

And what do we know about how the South African and Brazilian variants behave?

They are probably also more transmissible, because they share a number of mutations associated with transmissibility. As to whether they are more virulent or not, it is not clear. Probably not. And we don't know if they have the ability to evade the vaccine.

Do we have to restrict the entry of people from the UK and South Africa to our territory to stop the entry of the variants?

— The vaccination window we are in now is quite critical and we would have to avoid new variant infections as much as possible. Now we will find people with only one vaccine dose and between the first and second dose we have to avoid infection as much as possible, because there is a danger that these variants become resistant to vaccination in people who have been incompletely vaccinated. Restricting the entry of people from countries where these variants circulate more is a measure that, at this time, I would see as appropriate.