COVID-19 Symptoms and death | Recovery Coaching

Evidence from vaccine use during the pandemic shows vaccination can reduce infection and is most effective at preventing severe COVID-19 symptoms and death, but is less good at preventing mild COVID-19. Efficacy wanes over time but can be maintained with boosters.[218] In 2021, the CDC reported that unvaccinated people were 10 times more likely to be hospitalized and 11 times more likely to die than fully vaccinated people.[219][220]

The CDC reported that vaccine effectiveness fell from 91% against Alpha to 66% against Delta.[221] One expert stated that "those who are infected following vaccination are still not getting sick and not dying like was happening before vaccination."[222] By late August 2021, the Delta variant accounted for 99 percent of U.S. cases and was found to double the risk of severe illness and hospitalization for those not yet vaccinated.[223]

In November 2021, a study by the ECDC estimated that 470,000 lives over the age of 60 had been saved since the start of the vaccination roll-out in the European region.[224]

On 10 December 2021, the UK Health Security Agency reported that early data indicated a 20- to 40-fold reduction in neutralizing activity for Omicron by sera from Pfizer 2-dose vaccinees relative to earlier strains. After a booster dose (usually with an mRNA vaccine),[225] vaccine effectiveness against symptomatic disease was at 70%–75%, and the effectiveness against severe disease was expected to be higher.[226]

According to early December 2021 CDC data, "unvaccinated adults were about 97 times more likely to die from COVID-19 than fully vaccinated people who had received boosters".[227]

A meta-analysis looking into COVID-19 vaccine differences in immunosuppressed individuals found that people with a weakened immune system are less able to produce neutralizing antibodies. For example, organ transplant recipients need three vaccines to achieve seroconversion.[228] A study on the serologic response to mRNA vaccines among patients with lymphoma, leukemia, and myeloma found that one-quarter of patients did not produce measurable antibodies, varying by cancer type.[229]

In February 2023, a systematic review in The Lancet said that the protection afforded by infection was comparable to that from vaccination, albeit with an increased risk of severe illness and death from the disease of an initial infection.[230]

A January 2024 study by the CDC found that staying up to date on the vaccines could reduce the risk of strokes, blood clots and heart attacks related to COVID-19 in people aged 65 years or older or with a condition that makes them more vulnerable to said conditions.[231][232]

Duration of immunity

As of 2021, available evidence shows that fully vaccinated individuals and those previously infected with SARS-CoV-2 have a low risk of subsequent infection for at least six months.[233][234][235] There is insufficient data to determine an antibody titer threshold that indicates when an individual is protected from infection.[233] Multiple studies show that antibody titers are associated with protection at the population level, but individual protection titers remain unknown.[233] For some populations, such as the elderly and the immunocompromised, protection levels may be reduced after both vaccination and infection.[233] Available evidence indicates that the level of protection may not be the same for all variants of the virus.[233]

As of December 2021, there are no FDA-authorized or approved tests that providers or the public can use to determine if a person is protected from infection reliably.[233]

As of March 2022, elderly residents' protection against severe illness, hospitalization, and death in English care homes was high immediately after vaccination, but protection declined significantly in the months following vaccination.[236] Protection among care home staff, who were younger, declined much more slowly.[236] Regular boosters are recommended for older people, and boosters for care home residents every six months appear reasonable.[236]

The US Centers for Disease Control and Prevention (CDC) recommends a fourth dose of the Pfizer mRNA vaccine as of March 2022 for "certain immunocompromised individuals and people over the age of 50".[237][238]

Immune evasion by variants

In contrast to other investigated prior variants, the SARS-CoV-2 Omicron variant [239][240][241][242][243] and its BA.4/5 subvariants[244] have evaded immunity induced by vaccines, which may lead to breakthrough infections despite recent vaccination. Nevertheless, vaccines are thought to provide protection against severe illness, hospitalizations, and deaths due to Omicron.[245]

Vaccine adjustments

Effectiveness against transmission

As of 2022, fully vaccinated individuals with breakthrough infections with the SARS-CoV-2 delta (B.1.617.2) variant have a peak viral load similar to unvaccinated cases and can transmit infection in household settings.[252]

Mix and match

According to studies, the combination of two different COVID‑19 vaccines, also called cross-vaccination or the mix-and-match method, provides protection equivalent to that of mRNA vaccines, including protection against the Delta variant. Individuals who receive the combination of two different vaccines produce strong immune responses, with side effects no worse than those caused by standard regimens.[253][254]

Adverse events

For most people, the side effects, also called adverse effects, from COVID‑19 vaccines are mild and can be managed at home. The adverse effects of the COVID‑19 vaccination are similar to those of other vaccines, and severe adverse effects are rare.[255][256] Adverse effects from the vaccine are higher than placebo, but placebo arms of vaccine trials still reported adverse effects that can be attributed to the nocebo effect.[257]

All vaccines that are administered via intramuscular injection, including COVID‑19 vaccines, have side effects related to the mild trauma associated with the procedure and the introduction of a foreign substance into the body.[258] These include soreness, redness, rash, and inflammation at the injection site. Other common side effects include fatigue, headache, myalgia (muscle pain), and arthralgia (joint pain), all of which generally resolve without medical treatment within a few days.[11][12] Like any other vaccine, some people are allergic to one or more ingredients in COVID‑19 vaccines. Typical side effects are stronger and more common in younger people and in subsequent doses, and up to 20% of people report a disruptive level of side effects after the second dose of an mRNA vaccine.[259] These side effects are less common or weaker in inactivated vaccines.[259] COVID‑19 vaccination-related enlargement of lymph nodes happens in 11.6% of those who received one dose of the vaccine and in 16% of those who received two doses.[260]

Experiments in mice show that intramuscular injections of lipid excipient nanoparticles (an inactive substance that serves as the vehicle or medium) cause particles to enter the blood plasma and many organs, with higher concentrations found in the liver and lower concentrations in the spleen, adrenal glands, and ovaries. The highest concentration of nanoparticles was found at the injection site itself.[261]

COVID‑19 vaccination is safe for breastfeeding people.[13] Temporary changes to the menstrual cycle in young women have been reported. However, these changes are "small compared with natural variation and quickly reverse."[262] In one study, women who received both doses of a two-dose vaccine during the same menstrual cycle (an atypical situation) may see their next period begin a couple of days late. They have about twice the usual risk of a clinically significant delay (about 10% of these women, compared to about 4% of unvaccinated women).[262] Cycle lengths return to normal after two menstrual cycles post-vaccination.[262] Women who received doses in separate cycles had approximately the same natural variation in cycle lengths as unvaccinated women.[262] Other temporary menstrual effects have been reported, such as heavier than normal menstrual bleeding after vaccination.[262]

Serious adverse events associated COVID‑19 vaccines are generally rare but of high interest to the public.[263] The official databases of reported adverse events include

the World Health Organization's VigiBase;
the United States Vaccine Adverse Events Reporting System (VAERS);
the United Kingdom's Yellow Card Scheme;
the European Medicines Agency's EudraVigilance system, which operates a regular transfer of data on suspected adverse drug reactions occurring in the EU to WHO's Uppsala Monitoring Centre.[264]

Increased public awareness of these reporting systems and the extra reporting requirements under US FDA Emergency Use Authorization rules have increased reported adverse events.[265] Serious side effects are an ongoing area of study, and resources have been allocated to try and better understand them.[266][267][268] Research currently indicates that the rate and type of side effects are lower-risk than infection. For example, although vaccination may trigger some side effects, the effects experienced from an infection could be worse. Neurological side effects from getting COVID‑19 are hundreds of times more likely than from vaccination.[269]

Documented rare serious effects include:

anaphylaxis, a severe type of allergic reaction.[270] Anaphylaxis affects one person per 250,000 to 400,000 doses administered.[259][271]
blood clots (thrombosis).[270] These vaccine-induced immune thrombocytopenia and thrombosis are associated with vaccines using an adenovirus system (Janssen and Oxford-AstraZeneca).[270] These affect about one person per 100,000.[259]
myocarditis and pericarditis, or inflammation of the heart.[270] There is a rare risk of myocarditis (inflammation of the heart muscle) or pericarditis (inflammation of the membrane covering the heart) after the mRNA COVID‑19 vaccines (Moderna or Pfizer-BioNTech). The risk of myocarditis after COVID‑19 vaccination is estimated to be 0.3 to 5 cases per 100,000 persons, with the highest risk in young males.[272] In an Israeli nation-wide population-based study (in which the Pfizer-BioNTech vaccine was exclusively given), the incidence rate of myocarditis was 54 cases out of 2.5 million vaccine recipients, with an overall incidence rate of 2 cases per 100,000 persons, with the highest incidence seen in young males (aged 16 to 29) at 10 cases per 100,000 vaccine recipients. Of the cases of myocarditis seen, 76% were mild in severity, with one case of cardiogenic shock (heart failure) and one death (in a person with a preexisting heart condition) reported within the 83-day follow-up period.[273] COVID‑19 vaccines may protect against myocarditis due to subsequent COVID‑19 infection.[274] The risk of myocarditis and pericarditis is significantly higher (up to 11 times higher with respect to myocarditis) after COVID‑19 infection as compared to COVID‑19 vaccination, with the possible exception of younger men (less than 40 years old) who may have a higher risk of myocarditis after the second Moderna mRNA vaccine (an additional 97 cases of myocarditis per 1 million persons vaccinated).[274]

thrombotic thrombocytopenia and other autoimmune diseases, which have been reported as adverse events after the COVID‑19 vaccine.[275]

There are rare reports of subjective hearing changes, including tinnitus, after vaccination.[271][276][277][278]

Society and culture

Distribution

Main article: Deployment of COVID-19 vaccines

Note about the table in this section: number and percentage of people who have received at least one dose of a COVID‑19 vaccine (unless noted otherwise). May include vaccination of non-citizens, which can push totals beyond 100% of the local population. The table is updated daily by a bot.[note 2]

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Updated April 29, 2024.

As of 3 January 2024, 13.53 billion COVID-19 vaccine doses have been administered worldwide, with 70.6 percent of the global population having received at least one dose.[280][281] While 4.19 million vaccines were then being administered daily, only 22.3 percent of people in low-income countries had received at least a first vaccine by September 2022, according to official reports from national health agencies, which are collated by Our World in Data.[282]

During a pandemic on the rapid timeline and scale of COVID-19 cases in 2020, international organizations like the World Health Organization (WHO) and Coalition for Epidemic Preparedness Innovations (CEPI), vaccine developers, governments, and industry evaluated the distribution of the eventual vaccine(s).[283] Individual countries producing a vaccine may be persuaded to favor the highest bidder for manufacturing or provide first-class service to their own country.[284][285][286] Experts emphasize that licensed vaccines should be available and affordable for people at the frontlines of healthcare and in most need.[284][286]

In April 2020, it was reported that the UK agreed to work with 20 other countries and global organizations, including France, Germany, and Italy, to find a vaccine and share the results, and that UK citizens would not get preferential access to any new COVID‑19 vaccines developed by taxpayer-funded UK universities.[287] Several companies planned to initially manufacture a vaccine at artificially low prices, then increase prices for profitability later if annual vaccinations are needed and as countries build stock for future needs.[286]

The WHO had set out the target to vaccinate 40% of the population of all countries by the end of 2021 and 70% by mid-2022,[288] but many countries missed the 40% target at the end of 2021.[289][290]