Covid-19 Vaccination

The information on the COVID-19 changes every day and it is getting difficult for people to catch up with the latest situation.  Therefore, Marina Medical will like to contribute by providing what we have learned and organised them in a way that hopefully, you can understand and get yourself prepared. We will actively update on anything new that we have learned.

Written by Dr Ivan Chow (December 14, 2020.  HKT 10:00)

Information from World Health Organization, UpToDate Inc, Pfizer, Moderna, AstraZeneca, the Lancet, The New England Journal of Medicine

Declaration of Interest: Nil

Latest Update
Latest Update

December 11 2020

A press conference was held on December 11, 2020, by the government, Hong Kong has reached agreements with two COVID-19 vaccine manufacturers (Sinovac and Pfizer), securing 15 million shots, the first million of which could be available as early as January. 

The Government will soon reach a deal with a third manufacturer (AstraZeneca) which will also provide 7.5 million doses to the city.

January 7 2021

Dr Thomas Tsang Ho Fai, a member of the government's vaccination program task force said on a radio program that authorities are planning to set up vaccination centers at 18 districts in the city and start the vaccinations early February 2021. The first batch of 1 million doses of vaccine are produced by Sinovac, a mainland pharmaceutical company.

According to Reuters, the vaccine developed by China’s Sinovac Biotech was 78% effective in a late-stage Brazilian trial with no severe COVID-19 cases. There is no detailed data available yet.

Pfizer and BioNTech
Pfizer and BioNTech

Pfizer and BioNTech

On December 8, 2020, the United Kingdom has become the world's first nation to begin vaccinating its citizens with a fully vetted and authorized COVID-19 shot, a landmark moment in the coronavirus pandemic.[1]

On December 10, 2020, The New England Journal of Medicine has published safety and final efficacy results from Phase 3 trial of mRNA-based COVID-19 vaccine. It demonstrated the vaccine has an efficacy of 95%. Efficacy was consistent across age, gender, race and ethnicity demographics.

Side Effects

Local reaction including pain, swelling and redness at the injection site. Systemic events like fatigue, headache, muscle pain, and fever were reported, more often by younger recipients and more often after the second dose. For adverse events, 0.3% of recipients reported lymphadenopathy. No deaths were related to the vaccine.

Limitations

Follow-up time was 2 months only, the duration is not long enough to detect less common adverse events. Moreover, the duration of protection remains to be determined.[2] 

Storage

The recommended storage temperature condition is -70°C for up to 10 days unopened. Then the vaccine can be stored at refrigerated 2-8°C conditions for 5 days.

 

[1]https://www.pfizer.com/news/press-release/press-release-detail/pfizer-and-biontech-achieve-first-authorization-world

[2] https://www.pfizer.com/news/press-release/press-release-detail/pfizer-and-biontech-achieve-first-authorization-world

 

Moderna
Moderna

Moderna

On November 30, 2020, Moderna announced mRNA vaccine efficacy of 94.1% in Phase 3 study.[1] 

Side effects

Adverse events included injection site pain, erythema, redness, fatigue, myalgia, bone pain and headache which were generally short-lived.[2] 

Storage

The vaccine can remain stable at 2° to 8°C, the temperature of a standard home or medical refrigerator, for 30 days.

[1] https://investors.modernatx.com/news-releases/news-release-details/moderna-announces-primary-efficacy-analysis-phase-3-cove-study

[2] https://investors.modernatx.com/news-releases/news-release-details/modernas-covid-19-vaccine-candidate-meets-its-primary-efficacy

University of Oxford and AstraZeneca
University of Oxford and AstraZeneca

University of Oxford and AstraZeneca

On December 8, 2020, the Lancet has published safety and efficacy results of the replication-deficient chimpanzee adenoviral vector vaccine. In participants who received two standard doses, vaccine efficacy was 62.1% and in participants who received a low dose followed by a standard dose, the efficacy was 90.0%. .[1] 

Limitation

The median follow-up time was 3.4 months. It has not been able to assess the duration of protection.

Side Effects

Pain at the injection site was the most common local side effects. For systemic side effects, fatigue and headache were the most reported. Others side effects include muscle ache, malaise, chills and fever.

Three cases of transverse myelitis were reported as suspected unexpected serious adverse reactions, with two in the vaccine study arm, triggering a study pause. Independent clinical review of these cases has indicated that 2 cases are unlikely to be related to study interventions, but a relationship remained possible in the third case.[2] 

Storage

The vaccine can be stored, transported and handled at normal refrigerated conditions (2° to 8°C) for at least 6 months and administered within existing healthcare settings.

 

[1] Merryn V, Sue ACL, Shabir AM, et al. Safety and efficacy of the ChAdOx1 nCoV-19 vaccine (AZD1222) against SARS-CoV-2: an interim analysis of four randomised controlled trials in Brazil, South Africa, and the UK. Lancet. 2020; (published online Dec 8.) https://doi.org/10.1016/S0140-6736(20)32661-1

[2] Folegatti PM Ewer KJ Aley PK et al. Safety and immunogenicity of the ChAdOx1 nCoV-19 vaccine against SARS-CoV-2: a preliminary report of a phase 1/2, single-blind, randomised controlled trial. Lancet. 2020; 396: 467-478

Sinovac
Sinovac

Sinovac

On November 17, 2020, the Lancet has published the safety, tolerability, and immunogenicity of CoronaVac, an inactivated vaccine (phase 1/2 clinical trial). Seroconversion of neutralising antibodies was 92%-100%.[1] Phase 3 trial results are not available yet.

[1https://www.thelancet.com/journals/laninf/article/PIIS1473-3099(20)30843-4/fulltext

 

Vaccines Comparison table
Vaccines Comparison table

Vaccines comparison table

Company

Type of vaccine

Doses

Efficacy

Storage

Pfizer and BioNTech

RNA

2

95%

-70°C±10°C for up to 10 days unopened. 2-8°C conditions for 5 days.

Moderna

RNA

2

94.1%

-20°C for 6 months. 2°- 8°C for 30 days

University of Oxford and AstraZeneca

Replication-incompetent vector vaccines

2

62.1% - 90%

2° to 8°C for 6 months

 

When vaccines are ready to use?
When vaccines are ready to use?

When vaccines are ready to use? 

All vaccines must be proven safe and effective in large (phase III) clinical trials and a series of independent reviews of the efficacy and safety evidence is required.

Officials in individual countries decide whether to approve the vaccines for national use and develop policies for how to use the vaccines in their country based on the World Health Organization (WHO)  recommendations.

The vaccines must be manufactured in large quantities, which is a major and unprecedented challenge.

As a final step, all approved vaccines will require distribution through a complex logistical process, with rigorous stock management and temperature control.[1]

[1] https://www.who.int/news-room/q-a-detail/coronavirus-disease-(covid-19)-vaccines

 

What are Phase III clinical trials?
What are Phase III clinical trials?

What are Phase III clinical trials? 

These trials are designed to determine whether the vaccines prevent a disease. Subjects enrolled in phase III studies are randomly assigned and blinded to receipt of either vaccine or a control preparation (or comparator vaccine). Vaccine efficacy in percent is the reduction in specific disease incidence among those who received vaccine versus those who did not.[1]

Phase III clinical trials may not answer several efficacy questions related to SARS-CoV-2 vaccination. These include:

  • Duration of protection from disease
  • The potential need for and timing of additional booster doses
  • Effectiveness in subpopulations not evaluated in the clinical trials
  • Impact on community transmission

[1] https://www.uptodate.com/contents/coronavirus-disease-2019-covid-19-vaccines-to-prevent-sars-cov-2-infection?search=covid%20vaccine&source=search_result&selectedTitle=1~150&usage_type=default&display_rank=1

 

What are the different types of potential vaccines for COVID-19?
What are the different types of potential vaccines for COVID-19?

What are the different types of potential vaccines for COVID-19? 

  • Inactivated vaccines (e.g. Sinovac) are produced by growing SARS-CoV-2 in cell culture then chemically inactivating the virus. The inactivated virus in the vaccine stimulates an immune response[1]
  • Protein-based vaccines, which use harmless fragments of proteins or protein shells that mimic the COVID-19 virus to safely generate an immune response.[1]
  • Replication-incompetent vector vaccines (e.g. AstraZeneca) use a different vector virus that has been engineered to not replicate in the human body and to express the viral protein. Many replication-incompetent vector vaccine candidates use adenovirus vectors. One drawback to vector vaccines is that pre-existing immunity to the vector can attenuate immunogenicity of the vaccine. This can be avoided by using viral vectors that are uncommon in humans, vectors derived from animal viruses, such as a chimpanzee adenovirus.[1]
  • RNA vaccines (e.g. Pfizer, Moderna) were the first vaccines for SARS-CoV-2 to be produced and represent an entirely new vaccine approach. Once administered, the RNA is translated into the target protein, which is intended to elicit an immune response. Since the technology is new, the ability to produce large quantities of RNA vaccines has not been previously tested, and some of the vaccines must be maintained at very low temperatures, complicating storage.[1] It was believed that injecting RNA into a person does not do anything to the DNA of a human cell.

Fig. 1 How are vaccines created?

Fig. 2 What happens after the vaccine enters our body?

[1] https://www.uptodate.com/contents/coronavirus-disease-2019-covid-19-vaccines-to-prevent-sars-cov-2-infection-search=covid%20vaccine&source=search_result&selectedTitle=1~150&usage_type=default&display_rank=1

 

Questions not yet answered:
Questions not yet answered:

Questions not yet answered:

  1. How long after immunisation does it take to be protected?
  2. What is the estimated duration of protection?
  3. Can the vaccines prevent transmission?
  4. How the efficacy of the vaccines be affected by the cold-chain breach?
  5. What are the long-term side effects of the vaccines?
  6. Are the vaccines effective against all strains of SARS-CoV-2?
  7. Are the vaccines effective in all age and ethnic groups?
  8. Are the vaccines safe for an immunocompromised group and pregnant ladies?
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