Understanding Clinical Trials and the COVID-19 Vaccine

Clinical Trial - Vaccine: Covid-19, Coronavirus in vial with syringe on white background. Fake label.

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Recent public announcements by both Pfizer and Moderna suggest that vaccines for COVID-19 developed by these companies may be approved by the United States Food and Drug Administration (FDA) in the next several weeks.

Since the first case of COVID-19 was reported in China almost a year ago, the objective of the global scientific and medical community has been on the development of standard therapeutics to treat the virus as well as a vaccine to provide individuals with immunity.

Many pharmaceutical companies are making promising progress with their research. It is important to understand how this scientific research is done and how clinical trials work in developing new drugs or vaccines for COVID-19.

Why are clinical trials necessary?

Clinical trials are vital to help ensure new treatments and vaccines are safe for humans. They help clinicians determine how much of the product to prescribe and when, what side effects to expect, and which patients will likely benefit the most from the treatment or vaccine. Many drugs and treatments reach clinical trials, but never reach the public because they don’t work or they are harmful. This process reduces the risk of treatments coming to market that are not helpful or that are harmful.

During the pandemic, there was a lot of discussion about using drugs approved for other diseases to treat COVID-19 without clinical trials having shown benefit and safety. Is this a good idea?

“In the face of a pandemic as widespread, impactful, and potentially deadly as COVID-19 there was public pressure for physicians to administer medicines for COVID-19 that are approved for other diseases but with unknown benefit or even potential harm,” said R. Phillip Dellinger, MD, MSc, MCCM,  Professor of Medicine at Cooper Medical School of Rowan University. “Without meaningful studies, the medical community has no way of knowing if these medicines worked or not, or even if the patients simply recovered on their own with supportive care. Ideally, all of these unproven medications should be administered as part of a randomized clinical trial, as we do as a matter of routine research practice in normal times. Only then can we evaluate the safety and efficacy of these drugs or interventions.”

Why do clinical trials seem to take so long?

Clinical trials involve a series of methodical phases, according to Raquel Nahra, MD, infectious diseases specialist at Cooper. “Different vaccines have been developed and are currently enrolling volunteers around the world. The results of those trials are essential as part of management of one the worst public health crises that we have faced in over a 100 years.”

Below are the five phases of a clinical trial:

  • Phase 1 is conducted to see how the body processes a vaccine or medication and what effects it has. A very small dose is given to about 10 to 15 people.
  • Phase 2 determines the best dose of the vaccine or medication with the fewest side effects, and is tested in a small group of patients.
  • During Phase 3, the medication or vaccine is tested on a larger group of patients to further assess safety as well as effectiveness. There are currently several potential COVID-19 vaccines in this phase.
  • Phase 4 relies on a successful phase 3. During phase 4, the vaccine or medication is submitted to the FDA for approval.
  • Phase 5 follows approval by the FDA and includes the large-scale manufacturing of the approved vaccine or medication. Regulatory agencies continue to monitor production – inspecting manufacturing facilities and testing vaccines for potency, safety, and purity.

According to Dr. Nahra, large trials sponsored by the National Institutes of Health have already been conducted with the anti-viral drug Remdesivir, and it is currently approved for treatment of COVID-19 as a result. The most critical trial under way is the large-scale phase 3 trial assessing the efficacy and safety of the COVID-19 vaccines in development.


Comprensión de los Ensayos Clínicos y la Vacuna COVID-19

Los anuncios públicos recientes de Pfizer y Moderna sugieren que las vacunas para COVID-19 desarrolladas por estas compañías pueden ser aprobadas por la Administración de Drogas y Alimentos de los Estados Unidos (FDA) en las próximas semanas.

Desde que se informó el primer caso de COVID-19 en China hace casi un año, el objetivo de la comunidad científica y médica mundial ha sido el desarrollo de terapias estándar para tratar el virus, así como una vacuna para proporcionar inmunidad a las personas.

Muchas compañías farmacéuticas están logrando avances prometedores con sus investigaciones. Es importante comprender cómo se realiza esta investigación científica y cómo funcionan los ensayos clínicos para desarrollar nuevos medicamentos o vacunas para COVID-19.

¿Por qué son necesarios los ensayos clínicos?

Los ensayos clínicos son vitales para ayudar a garantizar que los nuevos tratamientos y vacunas sean seguros para los humanos. Ayudan a los médicos a determinar qué cantidad de producto recetar y cuándo, qué efectos secundarios esperar y qué pacientes probablemente se beneficiarán más del tratamiento o la vacuna. Muchos medicamentos y tratamientos llegan a ensayos clínicos, pero nunca llegan al público porque no funcionan o son dañinos. Este proceso reduce el riesgo de que salgan al mercado tratamientos que no son útiles o que son perjudiciales.

Durante la pandemia, hubo mucha discusión sobre el uso de medicamentos aprobados para otras enfermedades para tratar COVID-19 sin que los ensayos clínicos hayan demostrado beneficio y seguridad. ¿Es esta una buena idea?

“Frente a una pandemia tan extendida, impactante y potencialmente mortal como el COVID-19, hubo presión pública para que los médicos administraran medicamentos para el COVID-19 que están aprobados para otras enfermedades pero con un beneficio desconocido o incluso un daño potencial”, dijo R Phillip Dellinger, MD, MSc, MCCM, Profesor de Medicina en la Facultad de Medicina Cooper de la Universidad Rowan. “Sin estudios significativos, la comunidad médica no tiene forma de saber si estos medicamentos funcionaron o no, o incluso si los pacientes simplemente se recuperaron por sí mismos con cuidados de apoyo. Idealmente, todos estos medicamentos no probados deberían administrarse como parte de un ensayo clínico aleatorizado, como lo hacemos como práctica de investigación de rutina en tiempos normales. Solo entonces podremos evaluar la seguridad y eficacia de estos medicamentos o intervenciones “.

¿Por qué los ensayos clínicos parecen tardar tanto?

Los ensayos clínicos implican una serie de fases metódicas, según Raquel Nahra, MD, especialista en enfermedades infecciosas de Cooper. “Se han desarrollado diferentes vacunas y actualmente se están inscribiendo voluntarios en todo el mundo. Los resultados de esos ensayos son esenciales como parte de la gestión de una de las peores crisis de salud pública que hemos enfrentado en más de 100 años “.

A continuación, se muestran las cinco fases de un ensayo clínico:

  • Fase 1 se lleva a cabo para ver cómo procesa el cuerpo una vacuna o medicamento y qué efectos tiene. Se administra una dosis muy pequeña a aproximadamente 10 a 15 personas.
  • Fase 2 determina la mejor dosis de la vacuna o el medicamento con la menor cantidad de efectos secundarios y se prueba en un pequeño grupo de pacientes.
  • Durante Fase 3, el medicamento o la vacuna se prueba en un grupo más grande de pacientes para evaluar aún más la seguridad y la eficacia. Actualmente hay varias vacunas COVID-19 potenciales en esta fase.
  • Fase 4 se basa en una fase 3 exitosa. Durante la fase 4, la vacuna o el medicamento se envía a la FDA para su aprobación.
  • La fase 5 sigue a la aprobación de la FDA e incluye la fabricación a gran escala de la vacuna o el medicamento aprobados. Las agencias reguladoras continúan monitoreando la producción, inspeccionando las instalaciones de fabricación y probando las vacunas para determinar su potencia, seguridad y pureza.

Según el Dr. Nahra, ya se han realizado grandes ensayos patrocinados por los Institutos Nacionales de Salud con el medicamento antiviral Remdesivir y, como resultado, actualmente está aprobado para el tratamiento de COVID-19. El ensayo más crítico en curso es el ensayo de fase 3 a gran escala que evalúa la eficacia y seguridad de las vacunas COVID-19 en desarrollo.


  1. Avatar

    Thank you for your information about the process of developing treatment and vaccines for the Covid-19. It would be sincerely appreciated if you would continue to issue timely updates giving us your professional opinions as events continue to roll out very quickly every day and I am not sure we can rely on a lot of the mass of questionable data. Thank you very much.

    • Avatar

      Thank you for such information. Which is viltal to the human, to know how it would work. Understanding the process. But most importantly is the safely and we’ll being of all human, during this covid-19 crisis, thanks you for the vital information.

  2. Avatar James Connor

    It seems that the leading pharmaceuticals that are producing large quantities of Covid 19 vaccine have skipped phase 4 and gone directly to phase 5. The news media would have you believe that large amounts of the vaccine are rolling off the conveyor belts and I don’t believe they have reported FDA approval as of yet. No wonder everyone isn’t getting in line for the vaccine.

  3. Avatar vittal sitaram

    Please let us know once you have all the answers and recomend the availabality and definite safety especially for older persons. thanks.

  4. Avatar Tricia

    Do we know if the vaccine is going to be a one dose or every year vaccine? what is the percentage of people in the clinical trials that had adverse effects? will this vaccine be mandated for all employees?

  5. Avatar Helene Ehrke

    I agree with you 100%. It appears in my opinion they did in fact skip phase 4, by finishing 3 and bypassing 4 but rolling it into Phase 5.
    I and many others I know will NOT be taking “advantage” of this vaccine at this time. I still have too many questions and a low immune system due to lupus, HTLV I, Ii & III that there is very little information about. (After 30 years, no treatment or cure, when I go for doctors appointments and tell them about my viral blood cancer they look at me like I have an extra eye, and then I need to educate them on what little I know about it) so do you think I’m worried about taking the vaccine especially if they are giving a live one. Which is how you build up an immunity, not for me.
    It’s too new on the market. Let them work out all the kinks on others.
    Do you really think we are getting the same medicinal vaccine that the president would get, or anyone whom has a big enough bank account.
    If the manufacturers are so sure of their patent being approved by the FDA snd they are making you sign a document just in case something goes wrong snd by signing it. You are giving up any and all legal recourse against the mfg. etc..,..I don’t think so. This is the start of the end and start of a new beginning if you or I are lucky enough to be here or where ever the beginning will be. ????

  6. Avatar Margaret Williams

    Being a senior over 65-with a lung condition- how is one place on the list to be qualified to be in line & eligible for the vaccine for first recipients

  7. Avatar Alice Marsh

    I am a senior citizen at the age of 84 and I want to

    sign up for for Covid-19 to be sure I am protected
    I have battled several bouts of cancer and seem to to be doing well but I still think it is important to be covered and to protect myself with your help. I live in Willingboro, NJ
    Please Reply, Thankyou

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