This is the new “we have no evidence masks help” or “no evidence of asymptomatic spread”.

Name a vaccine that doesn’t reduce onward transmission even as it cures disease. It’s overwhelmingly likely that the vaccine will slow transmission and foolish to throw our priors in the garbage bin.

What we don’t know yet is how much onward transmission will be reduced.

"Name a vaccine that doesn’t reduce onward transmission even as it cures disease"

Whooping cough - that treats the symptoms but does not stop the patient from spreading the disease

Edit: Added context

I looked into this, and it does seem the vaccine reduces transmission. It just doesn’t stop it entirely. The paper below is Wikipedia’s source. Upon a close read, in the daycare there were three groups of vaccinated children:

* Those positive for antibodies but pcr negative —> had been exposed, cleared virus without infection

* those pcr positive but asymptomatic

* those pcr positive and symptomatic

About 30% were in the seropositive group which didn’t have pcr positivity. So it seems like transmission was reduced at least 30%. It’s also possible the other two groups would have had lower transmission rates than if they had had no vaccine.

If you have a more precise source I’d be interested to see it, but if this is the worst case it’s pretty good!

> We used PCR, EIA, and culture to confirm B. pertussis infection in two highly vaccinated groups of children in two day-care centers. Three (10%) of 30 2- to 3-year-old children were seropositive for recent infection; one had nasopharyngeal colonization and a clinical illness that met the modified WHO case definition. In the day-care center for the 5- to 6- year-old group, 9 (55%) of 16 children were IgM positive, 4 (25%) of whom had nasopharyngeal colonization. Of these four children, three had nonspecific cough, and only one met the modified WHO definition for pertussis. None of the children in our study, including those who met the WHO definition, had been examined by a physician before our investigation.

>Children who were seropositive and re- mained both asymptomatic and PCR negative probably had sufficient immunity from vaccines or natural boosters to protect them against persistent colonization and clinical disease. Their seropositivity could not be due to vaccine because the children were tested more than a year after having been vaccinated.

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2627963/pdf/109...

Name a disease where the measure of infection is a PCR test with a 40+ cycle threshold.

In this paper they've used 45 for HIV. What's your point?

https://www.hindawi.com/journals/art/2016/7954810/

> In this paper they've used 45 for HIV. What's your point?

There is a difference between HIV vs SARS-Cov2: If you get AIDS, your body does not have the capacity to recover from it on its own. So, 1) the chances of detecting dead material from a long gone infection are nil; and 2) the cost of a false negative is much higher than the cost of a false positive.

Since most people seem not to be seriously affected by a SARS-Cov2 infection, neither is true for SARS-Cov2. So, not agreeing on a fixed, reasonable, standard number of cycles which everyone uses has the consequence of inflating false positives for no gain. Note WHO's updated information[1].

> WHO guidance Diagnostic testing for SARS-CoV-2 states that careful interpretation of weak positive results is needed (1). The cycle threshold (Ct) needed to detect virus is inversely proportional to the patient’s viral load.

If you are not sick and your viral load is barely detectable, what's the point?

See also Figure 1 in WHO's lab guidance[2].

[1]: https://www.who.int/news/item/20-01-2021-who-information-not...

[2]: https://apps.who.int/iris/bitstream/handle/10665/334254/WHO-...

So you think they should use some lower Ct number for which it would be possible to show that eg 99.5% of people who are over it (i.e. have lower viral load) don't infect anyone? Interesting. I've read that most of the false negative for a PCR test actually come from sample collection (makes sense, PCR is super reliable) so it could be that you would miss people with high viral load where the sample was just not taken in a perfect way. Especially early in the infection it could be quite localized.

> So you think they should use some lower Ct number

Everyone should use the same number in all tests. From what I understand, about 20 is a reasonable number which might still result in positives up to a month post-infection. I consider having a standard more important that the specific number chosen. It seems when people go to > 30 it is in a quest to ensure a positive test result.

I fail to see what this has to do with vaccines and infectivity.

Also I’d only heard of people speak in terms of “positive” for pcr. You can be positive but not infectious, if there are a lot of cycles and you’re tested as the disease winds down.

Whats the normal cycle threshold for identifying pathogens? This is interesting.

Living in Israel I can tell you that the (current) plan involves masks and distancing for the entirety of 2021. We now have reasonable evidence that those vaccinated folks are still transmitters of the virus, and as of today, the majority of new cases in the last 48 hours were from the UK strain that targets children.

The real worry here is unfortunately human behaviour and not science. The science is clear, and it's been said/written/screamed/spraypainted that the #1 reason we have all of these restrictions is actually human behaviour as opposed to the virus itself.

>The science is clear, and it's been said/written/screamed/spraypainted that the #1 reason we have all of these restrictions is actually human behaviour as opposed to the virus itself.

Nope, if the virus didnt exist, there would be no restrictions; therefore, it is the primary reason.

Has there ever been a control group or any historical precedence to scientifically support the questionable hypothesis that a highly contagious virus can be can be globally controlled simply by controlling human behavior? (i.e. locking down entire nations while "essential workers" -- poor people -- are still forced to go to work)

Mere history won't stop us from trying to restrict human behavior into oblivion.

No evidence that it doesn't, either. It's simply hard to get this evidence and irrelevant for getting vaccines approved, so nobody has bothered. And it'd be really odd if it didn't help wrt infection rate.

Yeah, it would be great if the vaccine does prevent spread, but we should act like it doesn't until we know more.

As someone mentioned upthread, Israel will be an early indicator here.

Irellevent for getting it approved, not irellevent for herd immunity purposes

Well it's only 40% if you count only the over age 16 population. (Israel is not vaccinating under age 16 until more information.)

If you look at the entire population, it's only about 28% got 1st dose and 12% got second dose, many within the last week.

But with a population of about 9.3 million (size and population comparable to New Jersey) and they just ramped up to about 1million vaccinations a week, we could be at "full" vaccination March 26th - 85% of eligible population, 2nd dose, and 1 week for it to take affect.

Source: Israel's ministry of health https://datadashboard.health.gov.il/COVID-19/general and wikipedia's population information https://en.wikipedia.org/wiki/Demographics_of_Israel#Age_str...