Thread by @yaneslab

Here is my personal peer-review of #ENECovid19 project on the #seroprevalencia #seroprevalence of #COVID19 in Spain. Excellent work and document released yesterday by @SaludISCIII @sanidadgob @CienciaGob ciencia.gob.es/stfls/MICINN/M… (thread) 👇

Some background: These are preliminary results based on reading the IgG band of a rapid test for 60.897 participants. 97,55% of these participants did not have RT-PCR test for #COVID19.
The chosen rapid test is Orient Gene IgM / IgG from the company Zhejiang Orient Gene Biotech

According to the manufacturer, a sensitivity for IgM and IgG is 88% and 97% respectively, and a specificity of 100%. 3. Importantly, the degree of agreement for IgG measured by rapid test and by immunoassay in 16,953 samples analyzed so far is 97.3%.

The results of #ENECovid19 presented yesterday refer exclusively to the reading of the IgG band of the rapid test. The IgM band was not reported due to reading difficulties. Analyses by immunoassay are on the way

Age distribution of #ENECovid19

Yesterday, most people and news highlighted a 5% seroprevalence in the population. However there are some interesting details in #ENECovid19: 1) In relation to age, the prevalence is lower in babies, children and young people, remaining quite stable in older age groups.

For example, students (young population) showed almost half of the prevalence of IgG anti SARS-Cov2 antibodies than retired people (old population).

In addition, 87% of the participants with a RT-PCR + present IgG antibodies. In suspected cases, the prevalence increases with the number of symptoms and is particularly high in people who report anosmia (43%).

Remember that Spain (like Italy) has not implementing massive PCR testing in the population, unlike South Korea, Israel or Iceland. Therefore, the #seroprevalence (presence of IgG) and RT-PCR+ (presence of virus) by age reveal an interesting point in my opinion

From massive testing in South Korea, Israel and Iceland, we know that #COVID19 infects more the young. However, the young mainly show mild symptoms or are asymptomatic. Now we can also say that the young produce less IgG, if any...

When it comes to symptoms, the more symptoms the more % of IgG in that people. Interestingly, more than 50% of participants with #anosmia, which is probably the most specific symptom of #COVID19 infection, do not produce IgG.

So here is my naive question: if #COVID19 infects more young people, but young people present less symptoms, and those with less symptoms present less IgG, can we say that 95% of the population is not protected against covid19? can we say that only 5% has been infected?