A MAJOR British study into mixing COVID-19 vaccines has found that people had a better immune response when they received a first dose of AstraZeneca or Pfizer-BioNTech shots followed by Moderna nine weeks later, according to the results on Monday.

“We found a really good immune response across the board…, in fact, higher than the threshold set by Oxford-AstraZeneca vaccine two doses,” Matthew Snape, the Oxford professor behind the trial dubbed Com-COV2, told Reuters.

The findings supporting flexible dosing will offer some hope to poor and middle income countries which may need to combine different brands between first and second shots if supplies run low or become unstable.

“I think the data from this study will be especially interesting and valuable to low- and middle-income countries where they’re still rolling out the first two doses of vaccines,” Mr. Snape said.

“We’re showing…you don’t have to stick rigidly to receiving the same vaccine for a second dose…and that if the programme will be delivered more quickly by using multiple vaccines, then it is okay to do so.”

If the AstraZeneca-Oxford vaccine is followed by a Moderna or Novavax shot, higher antibodies and T-cell responses were induced versus two doses of AstraZeneca-Oxford, according to researchers at the University of Oxford.

The study of 1,070 volunteers also found that a dose of the Pfizer-BioNTech vaccine followed by a Moderna shot was better than two doses of the standard Pfizer-BioNTech course.

Pfizer-BioNTech followed by Novavax induced higher antibodies than the two-dose Oxford-AstraZeneca schedule, although this schedule induced lower antibody and T-cell responses than the two-dose Pfizer-BioNTech schedule.

No safety concerns were raised, according to the Oxford University study published in the Lancet medical journal.

Many countries have been deploying a mix and match well before robust data was available as nations were faced with soaring infection numbers, low supplies and slow immunization over some safety concerns.

Longevity of protection offered by vaccines has been under scrutiny, with booster doses being considered as well amid surging cases. New variants, including Delta and Omicron, have now increased the pressure to speed up vaccination campaigns.

Blood samples from participants were tested against the Wild-Type, Beta and Delta variants, researchers of the Com-COV2 study said, adding that vaccines’ efficacy against the variants had waned, but this was consistent across mixed courses.

Deploying vaccines using technology from different platforms — like Pfizer and Moderna’s mRNA, AstraZeneca’s viral vector and Novavax’s protein-based shot — and within the same schedule is new.

The results may inform new approaches to immunization against other diseases, he said.

The study also found that a first dose of the AstraZeneca-Oxford vaccine followed by any of the other candidates in the study generated a particularly robust response, consistent with findings in June.

The study was designed as a so-called “non-inferiority” study — the intent is to demonstrate that mixing is not substantially worse than the standard schedules — and compares the immune system responses to the gold-standard responses reported in previous clinical trials of each vaccine. — Reuters

WASHINGTON — The US House of Representatives could vote this week to raise the federal government’s $28.9-trillion debt limit, the chamber’s No. 2 Democrat told reporters on Monday, without providing details on how such an effort might unfold.

Treasury Secretary Janet Yellen has urged Congress to act by Dec. 15 and a bipartisan think tank warned last week the US government could run out of ways to cover its obligations by late this month, which would trigger an unprecedented default that would rock the global financial system.

“Hopefully we will be able to resolve a way that that (a debt limit bill) can be done in the next few days,” House Majority Leader Steny Hoyer told a news conference.

Top Republicans have been calling on President Joseph R. Biden’s Democrats to hike the debt limit without Republican votes, using a process known as reconciliation. Democrats note the increased debt is needed largely to cover the cost of tax cuts and spending programs during former President Donald Trump’s administration, which congressional Republicans supported.

But Democratic leaders in the House and Senate were searching for a way to win passage.

Senate Republicans also expressed optimism that Senate Majority Leader Chuck Schumer and his Republican counterpart, Mitch McConnell, would soon work out a debt ceiling agreement.

“I don’t think that anybody wants to see the full faith and credit of the United States damaged. And so, I’m an optimist,” Senator John Cornyn said after a meeting with Mr. McConnell and other leading Republican lawmakers.

Mr. Cornyn said he believes the Treasury could extend its debt ceiling deadline into January, possibly by using money from the Highway Trust Fund.

“But I don’t see any reason to delay the conversation,” he said of ongoing talks between Mr. Schumer and Mr. McConnell. “If they can get this behind us, I think we’d all be better off.”

Mr. Hoyer said it was possible that Democrats would attach the debt-hike initiative to a national defense authorization bill now moving through Congress.

A sizeable number of liberal Democrats voted against House passage of the defense bill and attaching the debt limit to it could ruin chances for getting enough Republican votes as well after the Senate passes a revised version.

AMONG SEVERAL MAJOR INITIATIVES
The debt limit is just one of several major initiatives that Democratic congressional leaders want to debate before the end of the year.

Mr. Schumer also wants additional votes on voting rights reforms, which have been repeatedly blocked by Senate Republicans, and Mr. Biden’s $1.75-trillion “Build Back Better” domestic investments bill this month.

Mr. Schumer noted that the Senate parliamentarian still has to review many components of the legislation, including an immigration provision, and decide whether they qualify to be included in the bill under a special budget reconciliation process that imposes tighter controls than regular legislation.

He did not say how he would advance voting rights legislation if Republicans engage in an expected filibuster that would require 60 votes in the 100-member chamber to break a deadlock. Many Democrats have been urging Mr. Schumer to push for a change in the Senate’s filibuster rule.

Last week, following a meeting Mr. Schumer held with a group of Democrats, Senator Jon Tester said he doubted a showdown over the filibuster could be staged this month given the Senate’s heavy legislative schedule.

“There’s just too much stuff on the docket,” he told Reuters. — Reuters