SANTIAGO (Reuters) - Earlier this month, Johnson & Johnson abruptly called for an end to enrollment in its coronavirus vaccine trial and told scientists from six Latin American countries to wrap up their work within 48 hours, two researchers told Reuters. The halt was due to J&J’s decision, announced later on that same day on Dec. 9, to cap the number of participants at about 40,000 people globally, down from a previous plan for 60,000. The drugmaker said that a surge in coronavirus cases in the areas it was testing would give it enough data to vet the vaccine. Our reporter participated in the Johnson & Johnson vaccine trial. Here"s how it went. Wrapping up recruitment more quickly - while continuing to monitor volunteers already participating - would keep J&J on target to seek U.S. authorization for the shot early next year, the company has said, if it proves successful against a virus that has already killed nearly 1.7 million people. J&J told Reuters it would not comment on its enrollment beyond a Friday statement that said the trial had closed. But the move has raised questions, and sparked disappointment, for some in Latin America, according to interviews with a dozen researchers, government officials and disease experts. Dr Miguel O’Ryan, leader of trials in three medical centers in and around Santiago, Chile, told Reuters his trials were abruptly closed to new volunteers after his team of 50 doctors and nurses had rushed to find people willing to take part in each age group. Researchers had been left “furious” that they weren’t given any prior warning and had to let down hundreds of people already scheduled to participate, he said. “At first they contact you, say they want all this, you get geared up and then overnight they tell you ‘that’s it,’” he said. “You understand the need to be more flexible... but it is hard for the research community in a study like this when the rules of the game change so quickly.” Peru, Chile, Mexico, Argentina, Brazil and Colombia had all offered to participate in the trial, hoping that would give them preferential access to J&J’s vaccine in the global race to stockpile doses. J&J told Reuters in September that those hosting trials would have priority for vaccine supply. Now some in government circles and the public health community fear those deals could be compromised. And local researchers have been left wondering whether they will be fully compensated for their investment in incomplete trials. J&J has not provided details on where the cap in numbers would impact most. The company did not comment on the status of supply deals or on compensation arrangements for researchers. The drugmaker expects an initial analysis of the data by late January. If the trial proves successful, the company plans to seek U.S. authorization in February. SEEKING SUPPLY To date, none of the six countries in Latin America participating in the trial has finalized a vaccine supply agreement with J&J, even though they still do not have enough doses from other vaccine makers to inoculate all of their citizens. Health officials in all six countries said that negotiations were still in progress. Albert Ko, professor of epidemiology at the Yale School of Public Health, who has extensive disease research experience in Latin America, said ensuring both rich and poor countries had good access to vaccines was a “key social justice issue for the world.” “Countries in Latin America, as they are establishing trial sites, need to pressure for these deals when they are negotiating with the industry. But also it’s on the companies,” he said. Ko cited the approach of AstraZeneca Plc to helping less wealthy nations produce and distribute its COVID-19 vaccine candidate, developed with Oxford University. AstraZeneca’s vaccine is viewed as one of the best hopes for many developing countries because of its cheaper price and ability to be transported at normal fridge temperatures. J&J turned to Latin America when infection rates there spiked, as a way to accelerate testing of the vaccine and gauge its effectiveness in diverse populations. The drugmaker shared its plans for the region with Reuters in September, saying it aimed to enroll 20,000 participants in the six countries by November. The J&J vaccine is easier to transport and store and is administered in a single shot, unlike vaccines from front-runners Pfizer Inc and Moderna Inc, which are delivered in two doses. J&J has signed an agreement in principle to provide the COVAX vaccine program with up to 500 million doses of its vaccine through 2022 for distribution to lower income countries. “This vaccine would be a game changer because of that single dose, not just for Latin America but for Asia, South Asia, sub-Saharan Africa and much of the world,” said Ko. “Two doses is exponentially more difficult to administer. I would think countries would jump on this if a safe and effective one-dose vaccine comes onboard.” Brazil has signed non-binding letters of intent to purchase vaccines from four companies including J&J, with health officials indicating a preference for the J&J single-dose shot. Mexico’s Deputy Health Minister Hugo Lopez-Gatell said earlier this month at a news conference that hosting the Janssen trial would give the country priority access to the vaccine. Foreign secretary Marcelo Ebrard said last week Mexico could order 22 million doses under a memorandum of understanding. The Mexican government declined to comment on the halting of trial recruitment and the likelihood now of a priority vaccine supply deal. A Peruvian government source told Reuters that new deals could be announced in the coming days, but declined to comment on which companies they could involve. The source said that there were constant surprises in the fast-moving negotiations taking place between governments and pharmaceutical companies around the world in the race to lock in deals, with intense and regular back-and-forth around price, quantity, delivery times and contractual conditions. Slideshow ( 4 images ) “Things change so fast that I could tell you something now and tomorrow it will be outdated,” he said. FAMILY AFFAIR During a conference call that Janssen - J&J’s pharmaceuticals division - convened with scientists from 100 Latin American trial sites on Dec. 9, local researchers, who had been working at full speed to help the company meet its ambitious goals, voiced their anger at the sudden announcement they should now wrap up their operations when their target volunteer numbers were not yet met and they had hundreds of people scheduled to be screened and vaccinated, according to two participants. J&J in the statement issued on Friday expressed “its thanks to all participants, trial sites and health care professionals involved in the ENSEMBLE study.” It did not comment on the angry reaction over the conference call. In all, the Latin American sites appear to have enrolled about 16,000 people, according to a Reuters tally of figures reported by trial leaders and governments. Any shortfall would be meaningful for individual research sites, who are paid based on the number of people they recruit. Reuters could not determine the range of what researchers are paid, which varies depending on a number of factors, including their specific locations, third-party partners and target size of trials. The urgency to sign people up quickly was evident at a site in Colina, Chile, late November, where a Reuters journalist was among the dozens of volunteers who moved along the queue in a narrow waiting room. Most of those volunteering were medical workers, the worst-hit by the pandemic, and their families. Trial staff also signed up their own families and friends to help make their numbers, they told Reuters. The start of trials in Chile, Peru and Mexico were delayed by several weeks, held up by factors like regulatory scrutiny, technical glitches and a scramble to get supplies. In Brazil, the effort began without a hitch in October, with people from all walks of life taking part, said a researcher. “There were thousands who volunteered. People are very enthusiastic to help and put up with long waits,” said Eduardo Vasconcellos, trial leader at the L2iP clinical research institute in Brasilia. Alejandra Camino, a trial investigator at privately-run DIM health clinics in the Argentine capital Buenos Aires, said that, although the abrupt end to enrollment was not ideal, it was important to remain flexible in the fight against COVID-19. “It’s a disappointment because if you set it up and found a venue, your operation is now going to be out of pocket,” she said of her colleagues’ work on their trials. “But we are talking about a pandemic.”