LONDON — The majority of people who have had coronavirus disease 2019 (COVID-19) are protected from getting it again for at least six months, a study published on Wednesday showed, but older people are more prone to reinfection than younger people.

The study, appearing in the Lancet medical journal, found that just 0.65% of patients tested positive a second time for COVID-19 after previously being infected during Denmark’s first and second waves. That was much lower than the 3.27% who were positive for the virus using highly accurate PCR tests after initially being negative.

However, the study found that people over the age of 65 had only 47% protection against repeat infection, compared to 80% protection for younger people.

“Our study confirms what a number of others appeared to suggest: reinfection with COVID-19 is rare in younger, healthy people, but the elderly are at greater risk of catching it again,” said Steen Ethelberg of Denmark’s Statens Serum Institut.

“Since older people are also more likely to experience severe disease symptoms, and sadly die, our findings make clear how important it is to implement policies to protect the elderly during the pandemic.”

The authors of the study found no evidence that protection against reinfection declined over a six month follow-up period, but said further studies were needed to assess protection against reinfection from variants of the coronavirus.

The data analyzed was collected through Denmark’s national testing strategy, under which 69% of the population, or 4 million people, were tested over the course of 2020.

Commenting on the results, Imperial College London professors Rosemary Boyton and Danny Altmann, said the results showed lower protection and were “more concerning” than previous studies.

“These data are all confirmation, if it were needed, that for SARS-CoV-2 the hope of protective immunity through natural infections might not be within our reach and a global vaccination programme with high efficacy vaccines is the enduring solution,” they said in a linked comment piece also published in the Lancet. — Reuters

FEDERAL RESERVE Chair Jerome Powell and his colleagues continued to project near-zero interest rates at least through 2023 despite upgrading their US economic outlook and the mounting inflation worries in financial markets.

The decision, which came on a volatile day for investors with Treasury yields surging ahead of the announcement, masked a growing number of officials who saw liftoff before then — though Mr. Powell stressed this remains a minority view.

“The strong bulk of the committee is not showing a rate increase during this forecast period,” Mr. Powell told a virtual press conference Wednesday following a meeting of the Federal Open Market Committee (FOMC), adding that the time to talk about reducing the central bank’s asset purchases was “not yet.”

Seven of 18 officials predicted higher rates by the end of 2023 compared with five of 17 at the December gathering, showing a slightly larger group who see an earlier start than peers to the withdrawal of ultra-easy monetary policy, according to fresh quarterly Fed projections.

“Indicators of economic activity and employment have turned up recently, although the sectors most adversely affected by the pandemic remain weak,” the FOMC said in its policy statement. “Inflation continues to run below 2%.”

The Fed expects that a bump in inflation this year will be short-lived. Officials saw their preferred measure of price pressures slowing to 2% next year following a spike to 2.4% in 2021, according to the projections. Excluding food and energy, inflation is forecast to hit 2.2% this year and fall to 2% in 2022.

Ten-year Treasury yields reversed their earlier rise as Powell spoke and US stocks closed higher.

Asked about the recent move up in yields, Mr. Powell pushed back against the idea the Fed should lean against the market, noting that the current stance of Fed policy, including its asset purchase program, was appropriate.

Massive fiscal support and widening vaccinations that will help reopen the economy have buoyed investor expectations for rate increases and inflation, propelling Treasury yields higher as the central bank and federal government keep adding stimulus.

The target range of the benchmark federal funds rate was kept at zero to 0.25%, where it’s been since last March. Wednesday’s FOMC decision was unanimous.

US central bankers left asset purchases unchanged at $120 billion a month and repeated that this pace would be maintained until “substantial further progress” is made on their employment and inflation goals. Mr. Powell told reporters that the Fed would signal well in advance when that threshold was on track to being achieved.

Mr. Powell and his colleagues met as the economy continues to improve. Job gains picked up last month and President Joseph R. Biden signed an additional $1.9 trillion of pandemic aid into law on Mar. 11. Vaccinations continue apace, allowing states to start easing lockdown restrictions that could release a torrent of consumer spending. 

The economy remains far from the Fed’s goals, though. Even with 379,000 jobs added to payrolls in February, 9.5 million fewer Americans have jobs compared with a year ago and inflation remains well below the Fed’s 2% target.

“This particular downturn was a direct hit on the part of the economy that employs many minorities,” Mr. Powell said.

Still, prospects for stronger growth have ignited some concern about higher inflation, contributing to a rise in 10-year Treasury yields in recent weeks. Mr. Powell told lawmakers in testimony last month that the economy still has a long way to go before there’s any risk of overheating.

They also upgraded forecasts for economic growth and the labor market, with the median estimate for unemployment falling to 4.5% at the end of 2021 and 3.5% in 2023, while gross domestic product was seen expanding 6.5% this year, up from a prior projection of 4.2%.

Christopher Waller, who joined the Board of Governors in late December, contributed projections for the first time this month. — Bloomberg