Canarian participation in the seroprevalence study drops to 47%

The Ministry of Health of the Government of the Canary Islands recently concluded the fourth wave of the National Epidemiological Survey of the infection by the SARS-CoV-2 virus in Spain 'ENE-COVID'. A study launched by the Ministry of Health in collaboration with the Carlos III Health Institute and the National Institute of Statistics (INE) to better understand the characteristics and temporal evolution of the COVID-19 pandemic in Spain.

In this fourth round, of the 7,784 eligible people (2,759 households), 7,773 were contacted, that is, 99.8% of the total, of which 3,658 agreed to participate, which represents 47.1% of the total.

The reasons for the dismissal of the selected persons were due to the refusal to participate in 2,799 cases, 68.17%; 1,185, 28.86%, did not attend the arranged appointment; and 111 people were not contacted, that is, 2.7%.

By islands, participation is distributed as follows: 412 people in Fuerteventura, 1,119 in Gran Canaria, 513 in Lanzarote, 201 in La Gomera, 196 in El Hierro, 363 in La Palma and 854 in Tenerife.

On this occasion, it was anticipated that participation, due to various concurrent factors, would be lower than that achieved in the three previous rounds, the main alleged reasons being the following: people who had already declined to participate in previous rounds; tiredness and lack of motivation in relation to the Study and their own perception of the pandemic, and work, school and other similar problems, which did not occur in the previous rounds, and which did not make it difficult for them to go to the Health Center.

Comparison between the four rounds

If the participation data of the third round is compared with the fourth round, it appears that the decrease stands at 24.23% overall for the entire Canary Islands. By islands, in Fuerteventura it has decreased by 18.41%, in Gran Canaria by 20.07%, in Lanzarote by 25.54%, in La Gomera by 27.95%, in El Hierro by 31.7%, in La Palma 23.58% and in Tenerife 28.41%.

A total of 4,527 people participated in the first round, distributed by islands as follows: Fuerteventura 485, Gran Canaria 1,245, Lanzarote 651, La Gomera 279, El Hierro 309, La Palma 434 and Tenerife 1,124.

For its part, in the second round there was an increase in participation, since 5,044 people agreed to join the Survey: 578 in Fuerteventura, 1,478 in Gran Canaria, 713 in Lanzarote, 292 in La Gomera, 301 in El Hierro, 455 in La Palma and 1,277 in Tenerife.

However, in the third round the number of participants decreased, reaching 4,828: 505 in Fuerteventura, 1,400 in Gran Canaria, 689 in Lanzarote, 279 in La Gomera, 287 in El Hiero, 475 in La Palma and 1,193 in Tenerife .

Once all the information derived from this fourth round has been processed and analyzed, consisting of the surveys carried out with the participants regarding different health, social, labor, etc. aspects related to the pandemic; the results of the rapid tests carried out in this wave, and the serological samples obtained, the national leaders of the ENE-COVID Survey and the Ministry of Health will make public the global results obtained both at the national level and those related to each Autonomous Community.

The Ministry of Health of the Government of the Canary Islands, aware that the results will be extremely useful when it comes to continuing to arbitrate measures to fight effectively against COVID-19, expresses its gratitude to the citizens who have participated in the different rounds and especially in this fourth wave, as well as all the health and administrative personnel of the Primary Care services and the SUC who have done a magnificent job to carry out the order received by this Ministry.

Fourth round of ENE-COVID

As it is a longitudinal study, the same population selected in the previous rounds has been recalled, which will allow an estimate of the behavior of the SARS-COV-2 infection, comparing the previous situation of confinement with the current incorporation to work and school life, and also learn about intra-household transmission.

In the previous edition, 5,807 people participated in the Canary Islands and a seroprevalence of between 2.7% and 2.3% was obtained according to the round, compared to 5% nationally.

ENE-COVID, the only study in the world of these characteristics, seeks to estimate the current seroprevalence of SARS-COV-2 infection by autonomous community, province, age and sex; estimate the mortality associated with COVID-19 by age and sex; estimate the duration of the antibodies and their effectiveness against reinfections, and obtain important information to guide managers on Public Health measures to combat the pandemic: precautionary measures, vaccination strategies, and any other useful measure.

Unlike the previous rounds, in this round all venipuncture samples will be analyzed at the National Microbiology Center and on this occasion this type of test was only performed on the selected population that was positive in any of the three previous rounds, a 15% of the seronegative of the previous rounds preselected with statistical criteria and the participants in this fourth round who tested positive for IgG in the rapid test that was performed on them.