No, it's not specific to COVID-19. People with Down Syndrome have weaker immune systems and they are much more susceptible to many infections, including flu. They also often suffer from congenital heart defects and respiratory issues which may decrease their resilience to COVID etc.
Yes, it is rather specific to COVID-19. From the article:
> But genetics may also make them particularly susceptible to SARS-CoV-2, the pandemic coronavirus. They have three copies of a gene on chromosome 21, TMPRSS2, which codes for an enzyme that the virus hijacks to help it enter human cells. The TMPRSS2 enzyme cleaves the spike protein that studs the virus’ surface, launching a series of steps that allows the virus to invade the host cell.
> Cells from people with DS typically express 1.6 times more TMPRSS2 than those from people without the condition
Well, yes, the mechanism that causes people with Down Syndrome to be susceptible to COVID is specific to COVID.
But I understood the questioner to be asking about respiratory infections in general (including flu) since the linked article already addresses COVID susceptibility.
> But genetics may also make them particularly susceptible to SARS-CoV-2, the pandemic coronavirus. They have three copies of a gene on chromosome 21, TMPRSS2, which codes for an enzyme that the virus hijacks to help it enter human cells. The TMPRSS2 enzyme cleaves the spike protein that studs the virus’ surface, launching a series of steps that allows the virus to invade the host cell.
> Cells from people with DS typically express 1.6 times more TMPRSS2 than those from people without the condition
