# Is the USA approaching herd immunity? **URL:** \ **Category:** The Quarantine Zone\ **Tags:** covid-quarantine\ **Created:** [February 5, 2021, 11:08am UTC](https://boards.straightdope.com/t/is-the-usa-approaching-herd-immunity/932256 "2021-02-05T11:08:30Z")\ **Posts on this page:** 1\ **Showing post:** 12
**Author:** ![Stranger\_On\_A\_Train](https://avatars.discourse-cdn.com/v4/letter/s/13edae/32.png) [@Stranger\_On\_A\_Train](https://boards.straightdope.com/u/Stranger_On_A_Train)\ **Post date:** [February 5, 2021, 9:50pm UTC](https://boards.straightdope.com/t/is-the-usa-approaching-herd-immunity/932256/12 "2021-02-05T21:50:55Z")
> [@Melbourne](#): > > Well there’s a problem right there, because, after extensive contact tracing, it’s well known ‘in Australia’ that the ‘mean number of replications per infection’ is not a useful number, because the variance is so large. Most people infect _nobody_ . A small number of people cause outbreaks. It’s ‘ _obvious to me_ ’ that if the people who cause outbreaks all become immune, the disease will decrease to a background level. > > Australia (where I live and which has had the contact tracing) has not had significant outbreaks of the new variants. My understanding is that most of the COVID in the USA is still ‘old variants’, so the present sharp decline reflects the behavior of ‘old variants’? It is certainly true that there is a skewness in the infection data, and that there are a relatively small minority fraction of infected people who are responsible for the majority of “superspreader” events where dozens or hundreds of people are infected; however, from what I’ve seen there is no good trending in the data to allow for predicting specific groups or individuals who are prone to this, and it isn’t clear how much of this is innate versus behavioral. At this point, I think we have to assume that individuals who are prone to much higher rates of transmitting the disease to others are more or less evenly distributed in the population such that inoculating a representative demographic cross section would still result in the same general replication number among uninoculated populations. In the US, we really have no idea just how widespread new variants are. The lack of genomic testing and surveillance is a stunning failure to take action to try to prevent wider contagion, with at least a few state health officials expressing the obtuse opinion that it didn’t matter which variant was dominant. Even with health departments stretched and labs worked to capacity, it would make sense to at least do enough sample testing of infectious people to get a statistically meaningful estimate, and we do not have that in any state to any degree of statistical confidence. > [@Melbourne](#): > > The sharp decline in January USA cases indicates that you are past the November infection spike, and that December did not cause an infection spike. This seems to be in contradiction to the idea that there was poor compliance in December. I have to disagree with that assessment. We see cases starting to rise in early December, which correlates with November (American Thanksgiving holiday, 26 November), and then at least a local peak in reported infections in early-to-mid-January for most states, which corresponds with Christmas-time gatherings, with a falloff in new cases after that as people stopped holiday gatherings _and_ some states got more serious about imposing restrictions. There are a few states that buck this trend but they tend to be rural states with lower population densities and also lower per capita rates of testing. There may have been better compliance in December indicated by the lower peaking in January than in December, but the trend of local peaking is still there. Regardless, at this point there is no reason to believe that we will assuredly achieve a herd immunity threshold without vaccination; aside from the native infectiousness of this pathogen, it is clear that at least in some significant percentage of people immune response wanes in a few months after exposure, which is consistent with what is known about other common human-infecting coronaviruses. With an effective vaccine and a vigorous inoculation campaign it should be possible to push this contagion down below the epidemic threshold and make it no more of a threat than influenza or any other of a number of infectious pathogens (provided, of course, that it doesn’t mutate into a really aggressive strain that evades the current crop of vaccines entirely, and even then, it is probably possible to make a vaccine that targets other parts of the capsid that are not as prone to mutation as the S-protein) but it does not appear that we would be able to get there via naturally acquired immunity through infection. Stranger --- _[View the full topic](https://boards.straightdope.com/t/is-the-usa-approaching-herd-immunity/932256)._