Thread by @SMImmunology

I have been tweeting about endemicity for a while now but I'll explain it here for anyone who wants to better understand how this pandemic will end from an immunologist's POW:
This pandemic won't end by us eradicating #SARS_CoV_2 there are three main reasons for this:

1) This virus has animal reservoirs meaning it can jump back and forth between humans and other hosts. So forget about we will eradicate this virus or COVIDzero
2) Although our vaccines are very effective against severe #COVID19 they don't confer sterilizing immunity meaning...

...you can be immunized and still get infected and transmit the virus.
3) Even if we had vaccines that conferred sterilizing immunity, we couldn't possibly vaccinate the entire human population to prevent the emergence of VOCs that can evade immunity...

This is also why #vaccineequity is so important but most industrialized countries don't pay attention to this.
Now that we know we can't eradicate the virus, we'll talk about how can the pandemic end (potentially):

Every time you have a maladapted virus infecting a new host the normal evolution for the virus if it wants to live with the host successfully is to become more transmissible (infect more hosts) and less virulent (cause less serious disease that could kill the host).

This is not only important to us but also to the virus itself. A successful virus is one that infects all of us without killing any of us or making us sick and we already have plenty of those. SARS-COV2 is no exception to this rule.

For a virus to get us to move from the pandemic to endemicity with a relatively mild respiratory disease, we would need a variant that would transmit efficiently between the hosts and infect a large portion of the population.

This variant should effectively outcompete other existing and emerging variants of SARS-COV2. The data so far from #Omicron is showing that it can efficiently transmit between hosts and it has replaced the #DeltaVariant pretty much everywhere that it became prevalent.

The other key important feature of such a variant to take us to endemicity is that the immunity that it will cause can neutralize the existing and emerging variants of SARS-COV2. The early data on this shows that Omicron infection can induce neutralizing antibodies against delta.

We will have more data on this as Omicron becomes dominant everywhere. So it appears that Omicron has all of these features: 1) it is highly transmissible and can outcompete other variants, 2) it will infect a big proportion of the society and induces broad immunity

These features of Omicron can induce #herdimmunity and push us to endemicity BUT there will be a cost and that will come from the smaller proportion of the population that will get sick to the point that they would need hospitalization.

Omicron can also effectively shut down different sectors of the economy as we will have more and more absentees because more people are getting infected and we are still managing the pandemic like March 2020. Here are the points to consider:

1) Mass vaccination/booster campaigns to reduce morbidity and mortality. We may have to consider making these vaccines mandatory for everyone working in high-risk settings such as hospitals, retirement homes, and schools.

The isolation periods should be modified and shortened and ideally paired with testing. Many governments are now trying this but we need to provide testing to reduce transmission in high-risk settings.

Please remember, we all got vaccinated for a day like this when we will inevitably face a highly contagious variant. If you think you can lockdown society forever or this virus will go away on its own think again. I welcome comments from other experts to add to this thread.

@sailorrooscout @EricTopol @BogochIsaac @zchagla @angie_rasmussen @MonicaGandhi9 @BallouxFrancois @ASPphysician