Margaret Keenan, a 90-year-old Briton, received the first coronavirus vaccine outside of clinical trials. It was on December 8, 2020, after an accelerated race never seen in history to have an effective defense against a virus. A study now published in the medical journal The Lancet has modeled what would have happened in the world if it had not been for vaccines or, better yet, how many lives they have saved: 19.8 million people, as many as if the covid had wiped out the entire population of Ecuador or half of the Argentines. The work also confirms the inequality in the distribution of those inoculated between poor and rich countries.
It is not easy to determine the impact of vaccines against covid. The trials showed that they had between 60% and 90% (depending on the formulation) of efficacy, understood as a reduction in the risk of suffering a serious covid. But how many deaths have they prevented? It is not easy to know. For that, it would be necessary to imagine two parallel worlds, one with vaccinated and others without vaccinating, and see where more people died from covid. Since such a comparison is impossible, one has to resort to mathematics and models. This is what researchers at Imperial College London (ICL) have done. With demographic data, including comorbidities, from 185 countries, health infrastructure, previous infection rate, vaccination rate and even types of vaccines, they modeled their impact on the world since Margaret Keenan was vaccinated until December 8, 2021, just a year later.
If the model is based on the statistics of deaths from covid, the vaccines would have prevented the death of 14.4 million people in the 185 countries studied. But not everywhere there is reliable official data. Not even in countries with advanced registration systems, as the case of Spain showed, did the figures reflect the real number of deaths from coronavirus. Therefore, another way of counting them was introduced. Deaths from all causes in 2020 or 2021 were counted and compared with deaths in pre-pandemic years. Thus, excess mortality could be attributed to the virus. On this basis, Oliver Watson, a researcher at the ICL Center for the Global Analysis of Infectious Diseases and lead author of the study, is clear: “We estimate that almost 20 million people would have died in a world without vaccines.”
According to the model, the vast majority of deaths avoided were due to the direct impact of the vaccine, that is, by being immunized. The rest would be due to indirect effects: herd immunity and decreased burden on the health system. The impact of the different vaccines was hardly noticed until mid-2021, when in the most advanced countries in vaccination the double guideline had already been completed, but most of the restrictions were lifted. This research also shows the differences, sometimes enormous, between some countries and others.
“Of the almost 20 million estimated deaths that would have been avoided in the first year after the arrival of the vaccines, about 7.5 million were in countries covered by the Initiative for Access to the Vaccine against Covid (Covax, for its acronym in English)”, says Watson. This mechanism promoted by the UN, WHO and the pro-vaccine alliance GAVI had as its mission the most equal access and distribution possible between the different countries. Covax set itself the goal of having at least 20% of the population of the hundred poorest countries vaccinated by the end of 2021. The WHO was even more ambitious, raising that goal to 40%. But the reality has been different. For example, the first vaccine arrived in Burundi, 10 months after the United States. While the American power had already bought enough vaccines to inoculate its entire population three times with the double schedule before they were available, only 0.07% of the inhabitants of the Democratic Republic of the Congo had received at least one dose at the end of 2021.
The time factor has been shown to be key. Vaccination began in Europe, the United States, Canada and other advanced countries much earlier than in the rest of the world and on a massive scale. “This meant that more deaths were averted as transmission increased in 2021, either by relaxing non-pharmaceutical interventions or by the arrival of the more transmissible Delta variant in the second half of the year. If vaccination had occurred before and prior to the arrival of this variant in low-income countries, more lives would have been saved”, comments the British researcher. “If the targets set by the WHO had been met, we estimate that around one in five lives lost to covid in less developed countries would have been prevented,” Watson said.
“If the targets set by the WHO had been met, we estimate that the loss of around one in five lives from covid in less developed countries would have been avoided”
Oliver Watson, Research Fellow at the Center for Global Analysis of Infectious Diseases at Imperial College London
The work also confirms that not all vaccines are the same. In those countries where those based on RNA technology (those from Moderna and Pfizer) carried the weight of vaccination, the number of lives saved has been greater. In addition to their greater efficacy, especially in the case of the Delta variant, these are vaccines with more demanding storage and transport conditions, which has meant that they barely reach many of those countries already punished for the delay of any vaccine. But the model has also detected a relative lower willingness to be vaccinated in many of the Covax countries and insufficient infrastructure to deploy the effort to vaccinate their inhabitants.
Professor Azra Ghani, Head of Infectious Disease Epidemiology at Imperial College London, highlights this in a note: “Our study demonstrates the enormous benefit that vaccines had in reducing Covid deaths globally. While the focus on the pandemic has shifted, it is important that we ensure that the most vulnerable people in all parts of the world are protected from the continued circulation of the disease… Ensuring equitable access to vaccines is critical, but it requires more than just donating vaccines. Improvements in infrastructure and distribution are needed, as well as coordinated efforts to combat misinformation about vaccines. Only then can we ensure that everyone has the opportunity to benefit from these life-saving technologies.”
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