NEW YORK — The effort to develop a safe and effective vaccine for COVID-19 has been an all-hands-on-deck approach ever since the virus began wreaking havoc across the globe earlier this year. But it seems now, with the presidential election less than two months away — and with President Trump promising a vaccine “very soon” — the pressure on vaccine developers has only mounted.

This, in turn, has raised concerns as to whether or not a vaccine — should one become available before November 3 — can be safe. To ease an already anxious public, the leaders of nine pharmaceutical companies recently issued a letter pledging that whatever COVID vaccine candidates they ultimately submit for approval to the Food and Drug Administration — whenever that may be — will have been fully vetted.

The pledge is essentially responding to fears that a vaccine might be rushed due to pressure from the White House as Trump seeks to find a “win” in the fight against the pandemic to boost his chances of ­reelection.

The letter makes sense, considering that the leading companies making the pledge — AstraZeneca, Johnson & Johnson, Moderna Inc., Novavax Inc., Merck, Sanofi, Glaxo­Smith­Kline and Pfizer Inc., which is developing a vaccine with BioNTech — are developing a candidate vaccine with at least some federal ­funding.

In pushing back against those fears, the chief executive officers affirm their “ongoing commitment to developing and testing potential vaccines for COVID-19 in accordance with high ethical standards and sound scientific principles.”

The safety and efficacy of vaccines, they state, including any potential vaccine for COVID-19, is reviewed and determined by expert regulatory agencies around the world, such as the FDA, which has established clear guidance for the development of COVID-19 vaccines and clear criteria for their potential authorization or approval in the U.S.

FDA’s guidance and criteria are based on the scientific and medical principles necessary to clearly demonstrate the safety and efficacy of potential COVID-19 vaccines. More specifically, the agency requires that scientific evidence for regulatory approval must come from large, high-quality clinical trials that are randomized and observer-blinded, with an expectation of appropriately designed studies with significant numbers of participants across diverse ­populations.

Specifically, the CEOs in their statement pledge to “always make the safety and well-being of vaccinated individuals our top priority; continue to adhere to high scientific and ethical standards regarding the conduct of clinical trials and the rigor of manufacturing processes; only submit for approval or emergency use authorization after demonstrating safety and efficacy through a Phase 3 clinical study that is designed and conducted to meet requirements of expert regulatory authorities such as FDA; and work to ensure a sufficient supply and range of vaccine options, including those suitable for global access.”

Last month, Pfizer and its partner, Germany-based BioNTech, shared additional Phase 1 safety and immunogenicity data from their ongoing U.S. study of the BNT162 mRNA-based vaccine program against SARS-CoV-2 (COVID-19), which has advanced into Phase 2/3 evaluation.

During a digital event earlier this month, Pfizer CEO Albert Bourla said the company has enrolled some 23,000 people for its Phase 3 trials and expects initial results by late October. If those results are positive, Pfizer would immediately seek FDA approval. Expecting the best outcome, Pfizer says it is already preparing its application in order to submit it as quickly as possible. The FDA has set an advisory panel meeting for October 22 to discuss COVID-19 vaccine progress.

For its part, Moderna continues to make gains in its Phase 3 clinical trial for its COVID candidate, mRNA-1273. In its weekly update earlier this month, Moderna said 21,411 patients were enrolled in the study.

The biotech is on pace to reach full enrollment — 30,000 — and has included a racially diverse set of participants, as different races can react differently to some drugs and vaccines, so a diverse population helps to ensure safety and efficacy across a wide spectrum of the public.

While completing enrollment in the clinical trials is essential for determining safety, the pace of enrollment, according to the scientific community, is actually more important for efficacy because developers cannot begin to evaluate how, and if, the vaccine works until the booster shot is given three to four weeks after the initial shot.

Stock in AstraZeneca, which is also on pace with Pfizer and Moderna, spiked after reports that the Trump administration was considering fast-tracking the drug maker’s vaccine candidate to make it available to Americans before election day.

Dr. Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases, said a vaccine could be available earlier than expected if ongoing clinical trials produce “overwhelmingly positive results.”

However, Fauci said in a recent interview: “If you are making a decision about the vaccine, you’d better be sure you have very good evidence that it is both safe and effective. Fauci, the nation’s leading infectious disease expert, also said he wasn’t concerned about “political pressure.”

In the meantime, the Centers for Disease Control and Prevention is prepping for possible vaccine deliveries by November 1. CDC director Robert Redfield recently asked states to consider waiving restrictions to ensure vaccine distribution sites could be up and running in short order.