You need to back this claim up with data please.

[1] https://www.bmj.com/content/374/bmj.n2113

““In my opinion, a reasonable worst case scenario could see protection below 50% for elderly people and healthcare workers by winter,” he said. “If there are high levels of infection in the UK, driven by loosened social restrictions and a highly transmissible variant, this scenario could mean increased hospitalisations and deaths. We urgently need to make plans for vaccine boosters and decide if a strategy to vaccinate children is sensible.””

See also https://www.medrxiv.org/content/10.1101/2021.08.24.21262423v...

Nothing past 6 months or so yet, but again the original British report which is discussed in the bmj article shows trend lines and it’s easy to extrapolate if you are good with charts/data.

"The overall age-adjusted vaccine effectiveness against infection for all New York adults declined from 91.7% to 79.8%." - https://www.cdc.gov/mmwr/volumes/70/wr/mm7034e1.htm?s_cid=mm...

"Two doses of mRNA vaccines were 74.7% effective against infection among nursing home residents early in the vaccination program (March–May 2021). During June–July 2021, when B.1.617.2 (Delta) variant circulation predominated, effectiveness declined significantly to 53.1%." - https://www.cdc.gov/mmwr/volumes/70/wr/mm7034e3.htm?s_cid=mm...

"The efficacy figure, which is based on an unspecified number of people between June 20 and July 17, is down from an earlier estimate of 64% two weeks ago and conflicts with data out of the U.K. that found the shot was 88% effective against symptomatic disease caused by the variant." - https://www.cnbc.com/2021/07/23/delta-variant-pfizer-covid-v...

"“As seen in real world data released from the Israel Ministry of Health, vaccine efficacy in preventing both infection and symptomatic disease has declined six months post-vaccination, although efficacy in preventing serious illnesses remains high,” the companies said in a written statement. “These findings are consistent with an ongoing analysis from the Companies’ Phase 3 study,” they said. “That is why we have said, and we continue to believe that it is likely, based on the totality of the data we have to date, that a third dose may be needed within 6 to 12 months after full vaccination.” ...... Executives from Pfizer and BioNtech have repeatedly said people will likely need a booster shot, or third dose, within 12 months of getting fully vaccinated because they expect vaccine-induced immunity to wane over time. They also said it’s likely people will need to get additional shots each year." - https://www.cnbc.com/2021/07/08/pfizer-says-it-is-developing...

So, while it's true that the effectiveness wanes, the same articles also point out that it is still effective at preventing severe hospitalization. If you're vaccinated, you're more likely after 6 months to get COVID anyway, but you are much less likely to be sent to the hospital or die.

77% efficacy against infection for Pfizer, 92% efficacy against infection for Moderna in the US.

Really wish people would stop saying vaccines have waned to uselessness. That just isn't even true for VE against infection. All the studies that I see at the lower level of ~50% VE against infection are highly problematic (there was a study of healthcare workers in San Diego where their unvaccinated control was only monitored via PCR for infection and only had a 3x increase of infections during the delta spike in Jul which suggests their unvaccinated controls had a significant amount of natural resistance or were taking many more precautions).

Your claim is frustrating because it is inaccurate and misleading.

"Vaccine efficacy, effectiveness and protection"

https://www.who.int/news-room/feature-stories/detail/vaccine...

Vaccine efficacy is found in trials, vaccine effectiveness is dynamic depending WHEN you calculate it and its found after 'deployment in the field'

"A vaccine’s efficacy is measured in a controlled clinical trial and is based on how many people who got vaccinated developed the ‘outcome of interest’ (usually disease) compared with how many people who got the placebo (dummy vaccine) developed the same outcome. Once the study is complete, the numbers of sick people in each group are compared, in order to calculate the relative risk of getting sick depending on whether or not the subjects received the vaccine. From this we get the efficacy – a measure of how much the vaccine lowered the risk of getting sick. If a vaccine has high efficacy, a lot fewer people in the group who received the vaccine got sick than the people in the group who received the placebo."

vs

"Vaccine effectiveness is a measure of how well vaccines work in the real world. Clinical trials include a wide range of people – a broad age range, both sexes, different ethnicities and those with known medical conditions – but they cannot be a perfect representation of the whole population. The efficacy seen in clinical trials applies to specific outcomes in a clinical trial . Effectiveness is measured by observing how well the vaccines work to protect communities as a whole. Effectiveness in the real world can differ from the efficacy measured in a trial, because we can’t predict exactly how effective vaccination will be for a much bigger and more variable population getting vaccinated in more real life conditions."

This very article is titled “experts say booster shots not needed”. Less frustrated people are statistically more likely to get that this means the essential benefits of vaccination have not (or not yet) deteriorated significantly.

As to with data from all age groups, they do so for both the value and the comparison. If you feel the need to split each population into subgroups, you would need continue doing so once you find, for example, what differs from the 20-year old that died vs the one that didn’t. In the end, each person would have their own group, because they all differ. But try doing any comparisons, then.

As far as age groups go, isn't there a pretty high correlation between high risk age groups for flu and high risk age groups for COVID?

As far as vaccine efficacy goes, the comment I decided to try to check the data on was comparing deaths, not infections. The mRNA vaccines in the US have had only a slight drop in the effectiveness at preventing death.