Spain is one of the countries that administered the highest percentage of the population with the second dose of the Covid-19 vaccine: 2.4% received both injections, which means they have protection complete offered by the vaccine. According to figures from Our World in Data, which is run by the University of Oxford in the UK, Spain is only behind Israel – which is clearly the world leader, with almost a third of the population. fully vaccinated – USA (4.83%), Denmark (2.99%), Romania (2.74%) and Serbia (2.67%).
But while this is good news – it means vaccines are delivered at a good rate as they are administered – there is another side to the coin. Studies indicate that a single dose of the vaccine can provide a high level of protection against Covid-19. This means that every second dose given could be seen as a blow that was not protecting another person.
The vaccination campaign in the UK follows this principle. While Spain administered a higher percentage of the population with the second dose than the UK, it is way behind the country on the first shot. In Spain, 3.5% of the population received the first dose of Covid, compared to 25% in the UK. This approach by Prime Minister Boris Johnson’s government was initially viewed with skepticism, but a growing body of research has come to support it.
A study published last Friday in the medical journal The Lancet shows that the Pfizer-BioNTech vaccine is 85% effective in symptomatic infections after the first dose. The investigation, which involved more than 7,000 workers at Sheba Medical Center in Tel Aviv, Israel, found a dramatic reduction in infection rates between 15 and 28 days after the first inoculation, reports Juan Carlos Sanz. For total coronavirus infections, including asymptomatic cases, Pfizer’s vaccine has been shown to be 75% effective. The results come after two Canadian scientists published a letter in the New England Journal of Medicine arguing that the first dose of Pfizer vaccine was 92.6% effective, according to studies by the pharmaceutical company itself and the US administration.
Although Canadian scientists admit that there are doubts about the duration of protection against a dose, they argue that giving a second vaccine after just one month has fewer short-term benefits. They write: “Given the current vaccine shortage, postponing the second dose is a matter of national security which, if ignored, will certainly result in thousands of Covid-19 hospitalizations and deaths this winter in the United States – hospitalizations and deaths this would have been avoided with the first dose of vaccine. “
Spain is following the guidelines of regulatory agencies: administer the second dose when it is time, according to the vaccine’s instructions. Amós García Rojas, president of the Spanish Vaccination Society, says new studies need to be reviewed as they are published to decide if this vaccination strategy needs to change, admitting that a lot can change very quickly depending on new data. But for now, he supports adherence to the protocol established by the European Medicines Agency (EMA), especially since the doses are expected to arrive faster, which means the population can be vaccinated faster.
In the case of the vaccine developed by Pfizer, the EMA recommends waiting 21 days before administering the second dose, but admits that this period can be extended to 42 days without impacting the effectiveness of the vaccine. These 21 days are not trivial. At Spain’s current rate, 1.3 million people could be vaccinated with the first dose of this period. Regarding Moderna and AstraZeneca’s Covid vaccine, the recommendation is to wait 28 days and 12 weeks, respectively, before administering the second dose.
Spain has already updated its vaccination protocol once before. In response to studies which showed that people who contracted the coronavirus developed a strong immune response, the Department of Health recommended that a person wait six months from the date of their diagnosis before being vaccinated.
The impact of the vaccination campaign is starting to show
All signs point to Spain starting to feel the effects of the vaccination campaign, launched at the end of December. Retirement homes, where more than 90% of residents have received both doses, are showing increasingly encouraging figures. Outbreaks in social service residences have fallen by 75% in the past month, more than double the decline recorded outside these centers. And a growing number of regions in Spain are reporting a drop in new coronavirus cases and deaths linked to Covid-19.
One of the most obvious cases of this fall is that of Asturias, which was also the Spanish region that most quickly vaccinated residents of health centers. The graph below shows the weekly number of coronavirus victims inside and outside social service residences. While at the start of 2020 the two categories followed the same pattern, they started to diverge three weeks into the vaccination campaign. The delay is understandable given that it can take 10 to 12 days for the vaccine to take effect and the number of deaths is the latest data point to reflect a drop in contagion. But three weeks after the vaccination campaign was launched, the lines of the graph started to diverge and the number of deaths outside care homes continued to rise, while deaths inside nursing homes continued to rise. care fell.
For this to be considered strong evidence of the vaccine’s impact, a study analyzing the data and removing other possible factors is needed. But Mario Margolles, director of the Asturias Health Observation, has little doubts about the significance of the numbers. “It is obvious that [the vaccines] have an effect because all other factors are the same and there is a decrease in mortality from the first dose. Seeing this makes us very excited and gives us a feeling of great relief, ”he says. The third wave of the coronavirus hit Asturias a bit later than the rest of Spain, and according to Margolles, that meant the vaccine had more time to make an impact and prevent hundreds of deaths. Margolles also admits that the vaccination campaign has shown that vaccines are not 100% effective. As studies show, they don’t work at least 5% of the time. “We are seeing infected cases more than a week after the second dose, but that was to be expected,” he explains. Studies, however, have shown that those who contract the coronavirus after receiving the vaccine have a much lower viral load, meaning the virus causes less severe symptoms or no symptoms, and levels of transmission are lower.
English version by Melissa Kitson.