Public Health Offers Reliable Information about Safety, Effectiveness of Updated COVID-19 Vaccine

This fall, many people are making appointments to get the updated COVID-19 vaccine, seeking additional protection against severe illness or hospitalization, and hoping to reduce their chances of spreading illness or needing to cancel activities. When faced with important medical choices, people typically have questions and the Los Angeles County Department of Public Health (Public Health) encourages residents to look to reliable sources for accurate information about the updated COVID-19 vaccine.

Among the most common questions Public Health hears are whether an updated COVID-19 vaccine is necessary if people have been previously infected with COVID-19 or had earlier versions of the vaccine. Research studies have shown that prior immunity against COVID-19 wanes over time. People who have been recently infected may consider delaying their COVID-19 vaccine dose by three months from symptom onset or positive test because they may have some protection from the virus after infection. Otherwise, it is good to update protection sooner rather than later.

In addition, the COVID-19 strains circulating now are different than what was circulating in 2020, when the first vaccine was widely administered, and last September, when the bivalent vaccine was introduced. With new strains, immunity from past vaccinations or infection may not be as strong.  The updated COVID-19 vaccine is formulated for strains that are found now, specifically Omicron XBB descendants, which account for 99 percent of sequenced specimens in Los Angeles County as of Sep. 16. For comparison, last winter, as of late Jan. 2023, only about 10 percent of specimens were descendants of XBB.

The best protection against severe illness from COVID-19 remains staying up to date on vaccines. At this time, being up to date means having received a dose of the updated COVID-19 vaccine since it became available last month. In some circumstances, this may be a person’s fifth or sixth dose.

The COVID-19 vaccine is safe and effective. More than 8.3 million people in Los Angeles County have received a COVID-19 vaccine dose since the start of the pandemic. Most people experience only mild side effects, like a sore arm or feeling a bit under the weather for a day or two, evidence that the immune system is building protection. Serious side effects have been extremely rare.

In fact, the chance of severe side effects is much lower than the risk of severe illness from COVID-19 itself. Over the past 30 days in Los Angeles County, people who were unvaccinated were three times more likely to be hospitalized and over four times more likely to die compared to those who were vaccinated. The benefits of being vaccinated — preventing severe illness, hospitalization, long COVID and death — greatly outweigh the very small risks of side effects.

It is recommended that everyone who is 6 months or older receives at least one dose of the updated COVID-19 vaccine. For children ages 4 years and younger, and for those who are immunocompromised, additional doses may be recommended. Providers can give additional information about timing and number of doses.

Myths about the COVID-19 vaccine continue to persist in the community, perpetuating vaccine hesitancy and preventing people from getting the most up-to-date protection.

There is no evidence of infertility from the vaccine among thousands of people who participated in clinical trials. In fact, many vaccine recipients have effectively conceived. Nor is there evidence of delayed puberty in children after receiving the COVID-19 or any other vaccine.

The mRNA vaccines cannot change DNA. The mRNA in the COVID-19 vaccine cannot enter the nucleus of the cell, where DNA lives. The mRNA helps activate an immune response to COVID-19, and then cells break down the mRNA without affecting other systems in the body.

For those who have questions about the vaccine, look for reliable sources. Oftentimes, the best sources may be your own health care provider.  If there is information online that questions the vaccine safety or effectiveness, it is good practice to check that the information is verified by multiple credible sources and written by a qualified physician, a health professional or distributed by a reputable institute or peer-reviewed journal. Online searches can help you to find the original source of the information posted on social media sites and it is good to bookmark the U.S. Centers for Disease Control and Prevention (CDC) COVID-19 page, which includes safety information, and Public Health’s vaccine page, including links to find sites offering vaccine.

In addition, Public Health continues to operate the Public Health Call Center, open seven days a week from 8 a.m. to 8 p.m., at 1-833-540-0473. Staff are available to answer questions about COVID-19 and the vaccine, and to direct people to resources if needed. This call line can also be used to find vaccine availability, schedule vaccine appointments and request a free homebound vaccine visit.

If someone is homebound or has difficulty leaving their home safely to get vaccinated against COVID-19, in-home vaccination can be requested. Self-referrals and referrals from organizations, agencies, providers, caregivers, family members, and loved ones are all welcome and others in the household can be vaccinated at the same time. Requests can also be made online at

In Los Angeles County, based on data through Sept. 30, the CDC Hospital Admission Level is Low at 5.2 new COVID-19 hospitalizations per 100,000 people, lower than 6.1 reported the week before.

Public Health reports COVID-19 data weekly. The following table shows case, wastewater, emergency department, hospitalization and death data in Los Angeles County over the past four weeks.


Date of Weekly Report





Daily average cases





SARS-CoV-2 wastewater concentration as a percentage of the Winter 2022-2023 peak concentration value





Daily average of the percent of Emergency Department (ED) encounters classified as coronavirus-related





Daily average number of COVID-positive hospitalizations





Daily average deaths





Percent of all deaths due to COVID-19





All daily averages are 7-day averages. Data for past weeks are subject to change in future reports. Time periods covered by each metric: cases = week ending each Saturday; wastewater = week ending each Saturday, with a one-week lag; ED data = week ending each Sunday; hospitalizations = week ending each Saturday; deaths = week ending each Monday, with a three-week lag; death percentage = week ending Monday, with a one-week lag.

Case data is presented by episode date, an approximation of the date the illness began, and death data is presented by date of death. This is a change from how case and death data were presented prior to July 26, 2023, which was by date of report. Daily average cases do not include Long Beach and Pasadena; daily average deaths include Long Beach and Pasadena.

Always check with trusted sources for the latest accurate information about novel coronavirus:

  • Los Angeles County Department of Public Health:

  • Centers for Disease Control and Prevention – Spanish:

Cases through 12:00pm 10/09/2023


Total Cases

Laboratory Confirmed Cases (includes LB and Pas through 6/27/23; excludes LB and Pas after 6/27/23)


Deaths (includes LB and Pas)


Cases by Age Group (Los Angeles County Cases Only-excl LB and Pas)

– 0 to 4


– 5 to 11


– 12 to 17


– 18 to 29


– 30 to 49


– 50 to 64


– 65 to 79


–  over 80


–  Under Investigation


Cases by Gender (Los Angeles County Cases Only-excl LB and Pas)

–  Female


–  Male


–  Other


–  Under Investigation


Cases by Race/Ethnicity (Los Angeles County Cases Only-excl LB and Pas)

–  American Indian/Alaska Native


–  Asian


–  Black


–  Hispanic/Latino


–  Native Hawaiian/Pacific Islander


–  White


–  Other


–  Under Investigation


Hospitalization (Los Angeles County Cases Only-excl LB and Pas)

–  Hospitalized (Ever)


Deaths by Race/Ethnicity (Los Angeles County Cases Only-excl LB and Pas)

–  American Indian/Alaska Native


–  Asian


–  Black


–  Hispanic/Latino


–  Native Hawaiian/Pacific Islander


–  White


–  Other


–  Under Investigation