The sixth wave of covid-19, starring the omicron variant, has multiplied infections both among those who are not vaccinated and those who are – in the last 14 days almost 1.4 million cases have been reported and there are thousands more unreported—but vaccines are proving very effective in protecting those infected from severe disease. Although specifying this level of protection is very complex, the partial data collected in Spain and the exhaustive analyzes carried out in the United Kingdom show that immunized people have much less risk of being hospitalized or dying from the virus.
The best information in Spain is offered by Catalonia, which shows data broken down by vaccination status. Analyzing the deaths in this autonomous community between December 23 and January 12 per 100,000 inhabitants, the mortality of people aged 70 or 80 is five times higher for the unvaccinated than for the immunized. And something similar happens in other ages. Thus, in this period, 50 deaths per 100,000 people have been reported among unvaccinated people aged 70 to 79, while among the immunized the figure is only 10 per 100,000, that is, five times less. Meanwhile, in the group of 60 to 69 years the difference is similar: the mortality of the unvaccinated is 15 deaths per 100,000 people; for those vaccinated, on the other hand, it is reduced to 5.5 per 100,000.
The Catalan data also show that the protection of vaccines is also noted in hospitals and intensive care units. For those immunized between 70 and 79 years of age, the probability of ending up hospitalized is almost six times lower than for those who have not received any dose. Meanwhile, the option of reaching the Intensive Care Units after becoming infected with covid is up to ten times less in the first group than in the second.
The Ministry of Health also publishes hospitalization data throughout Spain broken down by vaccination status, although in this case they make an estimate: to calculate the number of unvaccinated people in each age group, they subtract the number of vaccinated people from the population in 2020. However, the target population will have grown since then, so it is possible that the ministry’s calculations are overestimating the incidence among the unvaccinated. The figures yield similar conclusions: for people between 60 and 79 years old, for example, hospital admission rates are observed that are 18 times worse for the unvaccinated. This overestimation can explain why this figure is much higher than that of Catalonia.
In other countries, hospital data points to the same thing. In Italy, where the sixth wave is following a similar rhythm to that of Spain, the gap between vaccinated and unvaccinated is evident and remains over time. The probability of admission to hospital is ten times higher for the unvaccinated aged 60-79 years, a figure similar to that of Switzerland.
Booster doses restore protection
In the United Kingdom, the Health Security Agency (HSA) has analyzed in detail more than half a million omicron infections in the last weeks of 2021. In addition, to draw firm conclusions, when comparing the vaccinated and unvaccinated groups, they have take into account many factors that can influence your probability of contagion and income. They consider the age of the infected, their gender or the region where they live, but also if there are previous positives, if they have traveled to other countries or if they suffer from any pathology. Its objective is to monitor the effectiveness of vaccines, that is, to measure to what extent the risk of contagion, hospitalization or death of a person is reduced by the fact of being vaccinated.
Their results confirm that the vaccines continue to protect the immunized and that they do so especially from severe disease, but they also observe a loss of effectiveness as the weeks go by. At the beginning of receiving the second dose, the effectiveness of the vaccines against admission is around 72%, but drops to 52% in six months. In this sense, the good news is that booster doses raise protection again; for those over 65, for example, they reach 90%.
What happens to the infections in the omicron wave?
The new variant is very capable of infecting vaccinated people, as confirmed by studies in the United Kingdom: the effectiveness of two doses preventing symptomatic infections could drop almost to zero after six months, while with delta it remained at 40 %. Even after the booster dose, the effectiveness against omicron is partial, at rates between 40% and 60%, again with figures worse than those achieved against delta (90%).
These results are adjusted for many variables. In fact, when contagion rates are compared crude for vaccinated or unvaccinated people happens to be very similar or even worse for the vaccinated group compared to those who have not received any dose; this can happen, for example, if among the unvaccinated there are many more people who are naturally immunized from a previous infection. This last extreme may explain why some studies find apparently negative effects, as occurs in the reports from the United Kingdom or in a preliminary study in Denmark.
Something similar is observed in the official data from Iceland: the incidence is higher in the vaccinated population, without a booster dose, than among the unvaccinated (5,600 cases in 14 days per 100,000 people, compared to 4,000 in the unvaccinated group). . Of course, the lowest incidence occurs among Icelanders with three doses.
And the same is repeated in the data from Catalonia: in November the incidence was lower for the vaccinated than for the unvaccinated at all ages. But now, after the arrival of ómicron, among those under 50 years of age, who have barely received third doses, the infection rates seem to be higher in those vaccinated.
George Holan is chief editor at Plainsmen Post and has articles published in many notable publications in the last decade.