@Sarah977 If you look into the actual study you will find the quote to be very misleading. I'm pasting the original words from the John Hopkins website for it:
Johns Hopkins has conducted a large study on natural immunity that shows antibody levels against COVID-19 coronavirus stay higher for a longer time in people who were infected by the virus and then were fully vaccinated with mRNA COVID-19 vaccines compared with those who only got immunized. (The results of the study were published in a letter to the Journal of the American Medical Association on Nov. 1, 2021.)
It can be found here https://www.hopkinsmedicine.org/health/conditions-and-diseases/coronavirus/covid-natural-immunity-wh... BTW I can't find the source of your quote.
Basically, the study compared between natural immunity+vaccine against those who only had natural immunity. And the study was so fishy that they recruited patients who have had the disease 90 days before their first shot, knowingly that the natural immunity protection decays over time. Of course the result will be that people have had both would have better protection than one of them, not surprising. This only tells us that natural immunity and vaccine are not mutually exclusive and anyone can get the vaccine to improve the protection regardless of if he/she has had the disease before. It DOES NOT prove the vaccine does better job than natural immunity -- if you want to prove this comparison should be between the vaccine group and natural immunity group AT THE SAME TIME. As of the current knowledge we have, protection from both natural immunity and vaccine decay over time -- that is why it is suggested to have the booster.
Don't get me wrong. As a scientist I am not anti-vaxxer and I suggest everyone to get the vaccine if possible. However I do respect those who have valid concerns and decide not to take it at this time. At the end of day, the vaccine itself is quite experimental, with the technique never ever implemented by human in the history, that we have no knowledge about its long term side effects. At least for now, we know that it has a fairly high chance of causing myocarditis (which is already conceded by CDC) and doctors are even expecting a wave of myocarditis in the near future caused by the vaccine. There are just too many types of misinformation out there.