Background: Breast cancer is a major public health problem. Covid-19 pandemic impacted all areas of daily life, including medical care. In particular, delivering care for patients with cancer or suspected cancer during the crisis was challenging given the competing risks of death from untreated cancer versus serious complications from SARS-CoV-2, and the likely higher lethality of Covid-19 in immunocompromised patients. This study aims to assess the efficacy and immunogenicity of SARS-COV-2 vaccines in breast cancer patients by evaluating antispike antibodies in vaccinated and non-vaccinated patients and also through assessing the infection with Covid-19 after vaccination in vaccinated patients and non-vaccinated patients. The study also aims to assess the safety of SARS-COV-2 vaccine in breast cancer patients (local and systemic toxicity).  Methods: Our population consisted of 120 female patients diagnosed with early and locally advanced breast cancer (60 vaccinated and 60 unvaccinated against Covid-19), in the breast cancer unit, clinical oncology department, Ain Shams University Hospitals. All were on oncological systemic therapy (neoadjuvant or adjuvant treatment). The cutoff value of SARS COV-2 antibody is 50 AU/mL (≥ 50 seropositive, <50 seronegative). Results: Out of 120 patients, anti-SARS COV-2 antibody seropositivity was found to be 48 in non-vaccinated vs.58 in vaccinated patients (80% vs.96.7%), with p-value =0.0046, which was statistically significant. The median titre in both groups was found to be 1434.5 vs.2500, (p=0.0026). In the 120 patients, 26 patients had Covid-19 infection with a significant difference (p= 0.0004), with 21 (35%) non-vaccinated vs.5 (8.3 %) vaccinated. In the sixty vaccinated patients, mild local adverse events were reported such as warmness at site of injection in 17 (28.3%) patients, pain (11, 18.3%), swelling (11, 18.3%), itching (8, 13.3%), and redness (6, 10%) representing the least adverse event. The patients experienced mild systemic adverse events, the highest incidence was fatigue (28, 46.7%), then myalgia/arthralgia (17, 28.3%), headache (2, 3.3%), and fever (16, 26.7%). There was no statistical significance association between antispike Ab titre and age, stage, treatment types, and time since last vaccine.  Conclusion: SARS-COV-2 vaccines are effective and safe in localized breast cancer patients on systemic therapy.